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* Re: table inheritance versus column compression and storage settings
@ 2024-03-21 09:49 Peter Eisentraut <[email protected]>
0 siblings, 1 reply; 22+ messages in thread
From: Peter Eisentraut @ 2024-03-21 09:49 UTC (permalink / raw)
To: Ashutosh Bapat <[email protected]>; Tom Lane <[email protected]>; +Cc: pgsql-hackers
On 07.03.24 17:54, Ashutosh Bapat wrote:
> The pg_dump problems arise because we throw an error when parents have
> conflicting compression and storage properties. The patch that got
> reverted, changed this slightly by allowing a child to override parent's
> properties even when they conflict. It still threw an error when child
> didn't override and parents conflicted. I guess, MergeAttributes()
> raises error when it encounters parents with conflicting properties
> because it can not decide which of the conflicting properties the child
> should inherit. Instead it could just set the DEFAULT properties when
> parent properties conflict but child doesn't override. Thus when
> compression conflicts, child's compression would be set to default and
> when storage conflicts it will be set to the type's default storage.
> Child's properties when specified explicitly would override always. This
> will solve all the pg_dump bugs we saw with the reverted patch and also
> existing bug I reported earlier.
>
> This change would break backward compatibility but I don't think anybody
> would rely on error being thrown when parent properties conflict.
>
> What do you think?
At this point in the development cycle, I would rather not undertake
such changes. We have already discovered with the previous attempt that
there are unexpected pitfalls and lacking test coverage. Also, there
isn't even a patch yet. I suggest we drop this for now, or reconsider
it for PG18, as you wish.
^ permalink raw reply [nested|flat] 22+ messages in thread
* Re: table inheritance versus column compression and storage settings
@ 2024-03-21 11:16 Ashutosh Bapat <[email protected]>
parent: Peter Eisentraut <[email protected]>
0 siblings, 0 replies; 22+ messages in thread
From: Ashutosh Bapat @ 2024-03-21 11:16 UTC (permalink / raw)
To: Peter Eisentraut <[email protected]>; +Cc: Tom Lane <[email protected]>; pgsql-hackers
On Thu, Mar 21, 2024 at 3:19 PM Peter Eisentraut <[email protected]>
wrote:
> On 07.03.24 17:54, Ashutosh Bapat wrote:
> > The pg_dump problems arise because we throw an error when parents have
> > conflicting compression and storage properties. The patch that got
> > reverted, changed this slightly by allowing a child to override parent's
> > properties even when they conflict. It still threw an error when child
> > didn't override and parents conflicted. I guess, MergeAttributes()
> > raises error when it encounters parents with conflicting properties
> > because it can not decide which of the conflicting properties the child
> > should inherit. Instead it could just set the DEFAULT properties when
> > parent properties conflict but child doesn't override. Thus when
> > compression conflicts, child's compression would be set to default and
> > when storage conflicts it will be set to the type's default storage.
> > Child's properties when specified explicitly would override always. This
> > will solve all the pg_dump bugs we saw with the reverted patch and also
> > existing bug I reported earlier.
> >
> > This change would break backward compatibility but I don't think anybody
> > would rely on error being thrown when parent properties conflict.
> >
> > What do you think?
>
> At this point in the development cycle, I would rather not undertake
> such changes. We have already discovered with the previous attempt that
> there are unexpected pitfalls and lacking test coverage. Also, there
> isn't even a patch yet. I suggest we drop this for now, or reconsider
> it for PG18, as you wish.
>
>
I am fine with this. Should I mark the CF entry as RWF?
--
Best Wishes,
Ashutosh Bapat
^ permalink raw reply [nested|flat] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ messages in thread
From: Bertrand Drouvot @ 2025-11-04 13:52 UTC (permalink / raw)
Now that PGSTAT_KIND_RELATION is keyed by refilenode, we need to handle rewrites.
To do so, this patch:
- Adds PgStat_PendingRewrite, a new struct to track rewrite operations within
a transaction, storing the old locator, new locator, and original locator (for
rewrite chains). This allows stats to be copied from the original location to
the final location at commit time.
- Adds a new function, pgstat_mark_rewrite(), called when a table rewrite begins.
It records the rewrite operation in a local list and detects rewrite chains by
checking if the old_locator matches any existing new_locator, preserving the
chain's original_locator.
- Modifies pgstat_copy_relation_stats(), to accept RelFileLocators instead of
Relations, with a new increment parameter to accumulate stats (needed for rewrite
chains with DML between rewrites).
- Ensures that AtEOXact_PgStat_Relations(), AtPrepare_PgStat_Relations(),
pgstat_twophase_postcommit()/postabort() pgstat_drop_relation() handle the
PgStat_PendingRewrite list correctly.
Note that due to the new flush call in pgstat_twophase_postcommit() we can not
call GetCurrentTransactionStopTimestamp() in pgstat_relation_flush_cb(). So,
adding a check to handle this special case and call GetCurrentTimestamp() instead.
Note that we'd call GetCurrentTimestamp() only if there is a rewrite, so that
the GetCurrentTimestamp() extra cost should be negligible. Another solution
could be to trigger the flush from FinishPreparedTransaction() but that's not
worth the extra complexity.
The new pending_rewrites list is traversed in multiple places. The overhead
should be negligible in comparison to a rewrite and the list should not contain
a lot of rewrites in practice.
The pending_rewrites list is traversed in multiple places. In typical usage,
the list will contain only a few entries so the traversal cost is negligible (
furthermore in comparison to a rewrite).
---
src/backend/catalog/index.c | 2 +-
src/backend/commands/cluster.c | 5 +
src/backend/commands/tablecmds.c | 6 +
src/backend/utils/activity/pgstat_relation.c | 391 ++++++++++++++++++-
src/backend/utils/activity/pgstat_xact.c | 25 +-
src/backend/utils/cache/relcache.c | 6 +
src/include/pgstat.h | 5 +-
src/tools/pgindent/typedefs.list | 1 +
8 files changed, 424 insertions(+), 17 deletions(-)
92.8% 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] 22+ 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; 22+ 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] 22+ 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; 22+ 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] 22+ messages in thread
end of thread, other threads:[~2026-05-18 15:20 UTC | newest]
Thread overview: 22+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2024-03-21 09:49 Re: table inheritance versus column compression and storage settings Peter Eisentraut <[email protected]>
2024-03-21 11:16 ` Ashutosh Bapat <[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 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 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 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 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 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 v12 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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