pg.ddx.io pgsql-bugs@postgresql.org mailing list archive help / color / mirror / Atom feed From: Andres Freund <andres@anarazel.de>
Subject: [PATCH v4 4/6] wip: vacuum: Perform horizon determination just before starting scan.
Date: Fri, 10 Dec 2021 20:00:55 -0800
Author:
Reviewed-By:
Discussion: https://postgr.es/m/
Backpatch:
---
src/backend/access/heap/vacuumlazy.c | 157 ++++++++++++++++-----------
1 file changed, 96 insertions(+), 61 deletions(-)
inline patch 1: src/backend/access/heap/vacuumlazy.c (+96/-61 lines) download inline-1.patch diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 282b44f87bf..5145b9eee4b 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -288,6 +288,8 @@ typedef struct LVRelState
bool failsafe_active;
/* Consider index vacuuming bypass optimization? */
bool consider_bypass_optimization;
+ /* Should we scan all unfrozen pages? */
+ bool aggressive;
/* Doing index vacuuming, index cleanup, rel truncation? */
bool do_index_vacuuming;
@@ -308,6 +310,8 @@ typedef struct LVRelState
/* VACUUM operation's cutoff for freezing XIDs and MultiXactIds */
TransactionId FreezeLimit;
MultiXactId MultiXactCutoff;
+ /* visibility state for pruning */
+ GlobalVisState *vistest;
/* Error reporting state */
char *relnamespace;
@@ -377,11 +381,10 @@ static int elevel = -1;
/* non-export function prototypes */
-static void lazy_scan_heap(LVRelState *vacrel, VacuumParams *params,
- bool aggressive);
+static void lazy_scan_heap(LVRelState *vacrel, VacuumParams *params);
+static void lazy_scan_heap_limits(LVRelState *vacrel, VacuumParams *params);
static void lazy_scan_prune(LVRelState *vacrel, Buffer buf,
BlockNumber blkno, Page page,
- GlobalVisState *vistest,
LVPagePruneState *prunestate);
static void lazy_vacuum(LVRelState *vacrel);
static bool lazy_vacuum_all_indexes(LVRelState *vacrel);
@@ -417,7 +420,7 @@ static bool should_attempt_truncation(LVRelState *vacrel);
static void lazy_truncate_heap(LVRelState *vacrel);
static BlockNumber count_nondeletable_pages(LVRelState *vacrel,
bool *lock_waiter_detected);
-static int dead_items_max_items(LVRelState *vacrel);
+static int dead_items_max_items(LVRelState *vacrel);
static inline Size max_items_to_alloc_size(int max_items);
static void dead_items_alloc(LVRelState *vacrel, int nworkers);
static void dead_items_cleanup(LVRelState *vacrel);
@@ -465,11 +468,8 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
int usecs;
double read_rate,
write_rate;
- bool aggressive; /* should we scan all unfrozen pages? */
bool scanned_all_unfrozen; /* actually scanned all such pages? */
char **indnames = NULL;
- TransactionId xidFullScanLimit;
- MultiXactId mxactFullScanLimit;
BlockNumber new_rel_pages;
BlockNumber new_rel_allvisible;
double new_live_tuples;
@@ -478,9 +478,6 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
ErrorContextCallback errcallback;
PgStat_Counter startreadtime = 0;
PgStat_Counter startwritetime = 0;
- TransactionId OldestXmin;
- TransactionId FreezeLimit;
- MultiXactId MultiXactCutoff;
/* measure elapsed time iff autovacuum logging requires it */
if (IsAutoVacuumWorkerProcess() && params->log_min_duration >= 0)
@@ -502,27 +499,6 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
pgstat_progress_start_command(PROGRESS_COMMAND_VACUUM,
RelationGetRelid(rel));
- vacuum_set_xid_limits(rel,
- params->freeze_min_age,
- params->freeze_table_age,
- params->multixact_freeze_min_age,
- params->multixact_freeze_table_age,
- &OldestXmin, &FreezeLimit, &xidFullScanLimit,
- &MultiXactCutoff, &mxactFullScanLimit);
-
- /*
- * We request an aggressive scan if the table's frozen Xid is now older
- * than or equal to the requested Xid full-table scan limit; or if the
- * table's minimum MultiXactId is older than or equal to the requested
- * mxid full-table scan limit; or if DISABLE_PAGE_SKIPPING was specified.
- */
- aggressive = TransactionIdPrecedesOrEquals(rel->rd_rel->relfrozenxid,
- xidFullScanLimit);
- aggressive |= MultiXactIdPrecedesOrEquals(rel->rd_rel->relminmxid,
- mxactFullScanLimit);
- if (params->options & VACOPT_DISABLE_PAGE_SKIPPING)
- aggressive = true;
-
vacrel = (LVRelState *) palloc0(sizeof(LVRelState));
/* Set up high level stuff about rel */
@@ -569,11 +545,6 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
vacrel->relminmxid = rel->rd_rel->relminmxid;
vacrel->old_live_tuples = rel->rd_rel->reltuples;
- /* Set cutoffs for entire VACUUM */
- vacrel->OldestXmin = OldestXmin;
- vacrel->FreezeLimit = FreezeLimit;
- vacrel->MultiXactCutoff = MultiXactCutoff;
-
vacrel->relnamespace = get_namespace_name(RelationGetNamespace(rel));
vacrel->relname = pstrdup(RelationGetRelationName(rel));
vacrel->indname = NULL;
@@ -609,7 +580,7 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
* Call lazy_scan_heap to perform all required heap pruning, index
* vacuuming, and heap vacuuming (plus related processing)
*/
- lazy_scan_heap(vacrel, params, aggressive);
+ lazy_scan_heap(vacrel, params);
/* Done with indexes */
vac_close_indexes(vacrel->nindexes, vacrel->indrels, NoLock);
@@ -624,7 +595,7 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
if ((vacrel->scanned_pages + vacrel->frozenskipped_pages)
< vacrel->rel_pages)
{
- Assert(!aggressive);
+ Assert(!vacrel->aggressive);
scanned_all_unfrozen = false;
}
else
@@ -674,8 +645,16 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
if (new_rel_allvisible > new_rel_pages)
new_rel_allvisible = new_rel_pages;
- new_frozen_xid = scanned_all_unfrozen ? FreezeLimit : InvalidTransactionId;
- new_min_multi = scanned_all_unfrozen ? MultiXactCutoff : InvalidMultiXactId;
+ if (scanned_all_unfrozen)
+ {
+ new_frozen_xid = vacrel->FreezeLimit;
+ new_min_multi = vacrel->MultiXactCutoff;
+ }
+ else
+ {
+ new_frozen_xid = InvalidTransactionId;
+ new_min_multi = InvalidMultiXactId;
+ }
vac_update_relstats(rel,
new_rel_pages,
@@ -743,14 +722,14 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
* implies aggressive. Produce distinct output for the corner
* case all the same, just in case.
*/
- if (aggressive)
+ if (vacrel->aggressive)
msgfmt = _("automatic aggressive vacuum to prevent wraparound of table \"%s.%s.%s\": index scans: %d\n");
else
msgfmt = _("automatic vacuum to prevent wraparound of table \"%s.%s.%s\": index scans: %d\n");
}
else
{
- if (aggressive)
+ if (vacrel->aggressive)
msgfmt = _("automatic aggressive vacuum of table \"%s.%s.%s\": index scans: %d\n");
else
msgfmt = _("automatic vacuum of table \"%s.%s.%s\": index scans: %d\n");
@@ -770,7 +749,7 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
(long long) vacrel->tuples_deleted,
(long long) vacrel->new_rel_tuples,
(long long) vacrel->new_dead_tuples,
- OldestXmin);
+ vacrel->OldestXmin);
orig_rel_pages = vacrel->rel_pages + vacrel->pages_removed;
if (orig_rel_pages > 0)
{
@@ -888,7 +867,7 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
* supply.
*/
static void
-lazy_scan_heap(LVRelState *vacrel, VacuumParams *params, bool aggressive)
+lazy_scan_heap(LVRelState *vacrel, VacuumParams *params)
{
LVDeadItems *dead_items;
BlockNumber nblocks,
@@ -906,21 +885,10 @@ lazy_scan_heap(LVRelState *vacrel, VacuumParams *params, bool aggressive)
PROGRESS_VACUUM_MAX_DEAD_TUPLES
};
int64 initprog_val[3];
- GlobalVisState *vistest;
+ bool aggressive;
pg_rusage_init(&ru0);
- if (aggressive)
- ereport(elevel,
- (errmsg("aggressively vacuuming \"%s.%s\"",
- vacrel->relnamespace,
- vacrel->relname)));
- else
- ereport(elevel,
- (errmsg("vacuuming \"%s.%s\"",
- vacrel->relnamespace,
- vacrel->relname)));
-
nblocks = RelationGetNumberOfBlocks(vacrel->rel);
next_unskippable_block = 0;
next_failsafe_block = 0;
@@ -942,8 +910,6 @@ lazy_scan_heap(LVRelState *vacrel, VacuumParams *params, bool aggressive)
vacrel->num_tuples = 0;
vacrel->live_tuples = 0;
- vistest = GlobalVisTestFor(vacrel->rel);
-
vacrel->indstats = (IndexBulkDeleteResult **)
palloc0(vacrel->nindexes * sizeof(IndexBulkDeleteResult *));
@@ -968,6 +934,28 @@ lazy_scan_heap(LVRelState *vacrel, VacuumParams *params, bool aggressive)
initprog_val[2] = dead_items->max_items;
pgstat_progress_update_multi_param(3, initprog_index, initprog_val);
+ /*
+ * Compute vacuuming XID cutoffs.
+ *
+ * We do this as late as possible, as the limits determine how much work
+ * can be done now / how much has to be deferred till later.
+ * vac_open_indexes() may block, RelationGetNumberOfBlocks() can take a
+ * while on large relations, dead_items_alloc() isn't cheap, ...
+ */
+ lazy_scan_heap_limits(vacrel, params);
+ aggressive = vacrel->aggressive;
+
+ if (aggressive)
+ ereport(elevel,
+ (errmsg("aggressively vacuuming \"%s.%s\"",
+ vacrel->relnamespace,
+ vacrel->relname)));
+ else
+ ereport(elevel,
+ (errmsg("vacuuming \"%s.%s\"",
+ vacrel->relnamespace,
+ vacrel->relname)));
+
/*
* Except when aggressive is set, we want to skip pages that are
* all-visible according to the visibility map, but only when we can skip
@@ -1364,7 +1352,7 @@ lazy_scan_heap(LVRelState *vacrel, VacuumParams *params, bool aggressive)
* were pruned some time earlier. Also considers freezing XIDs in the
* tuple headers of remaining items with storage.
*/
- lazy_scan_prune(vacrel, buf, blkno, page, vistest, &prunestate);
+ lazy_scan_prune(vacrel, buf, blkno, page, &prunestate);
Assert(!prunestate.all_visible || !prunestate.has_lpdead_items);
@@ -1683,7 +1671,6 @@ lazy_scan_prune(LVRelState *vacrel,
Buffer buf,
BlockNumber blkno,
Page page,
- GlobalVisState *vistest,
LVPagePruneState *prunestate)
{
Relation rel = vacrel->rel;
@@ -1722,7 +1709,7 @@ retry:
* lpdead_items's final value can be thought of as the number of tuples
* that were deleted from indexes.
*/
- tuples_deleted = heap_page_prune(rel, buf, vistest,
+ tuples_deleted = heap_page_prune(rel, buf, vacrel->vistest,
InvalidTransactionId, 0, &nnewlpdead,
&vacrel->offnum);
@@ -2184,6 +2171,54 @@ lazy_vacuum(LVRelState *vacrel)
vacrel->dead_items->num_items = 0;
}
+/*
+ * Helper for lazy_scan_heap(), determining xid limits (vacrel->OldestXmin,
+ * vacrel->MultiXactCutoff) and whether the full relation should be scanned
+ * (vacrel->aggressive).
+ */
+static void
+lazy_scan_heap_limits(LVRelState *vacrel, VacuumParams *params)
+{
+ TransactionId xidFullScanLimit;
+ MultiXactId mxactFullScanLimit;
+ bool aggressive;
+
+ vacuum_set_xid_limits(vacrel->rel,
+ params->freeze_min_age,
+ params->freeze_table_age,
+ params->multixact_freeze_min_age,
+ params->multixact_freeze_table_age,
+ &vacrel->OldestXmin, &vacrel->FreezeLimit,
+ &xidFullScanLimit,
+ &vacrel->MultiXactCutoff,
+ &mxactFullScanLimit);
+
+ /*
+ * We request an aggressive scan if the table's frozen Xid is now older
+ * than or equal to the requested Xid full-table scan limit; or if the
+ * table's minimum MultiXactId is older than or equal to the requested
+ * mxid full-table scan limit; or if DISABLE_PAGE_SKIPPING was specified.
+ */
+ aggressive = TransactionIdPrecedesOrEquals(vacrel->rel->rd_rel->relfrozenxid,
+ xidFullScanLimit);
+ aggressive |= MultiXactIdPrecedesOrEquals(vacrel->rel->rd_rel->relminmxid,
+ mxactFullScanLimit);
+ if (params->options & VACOPT_DISABLE_PAGE_SKIPPING)
+ aggressive = true;
+ vacrel->aggressive = aggressive;
+
+ /*
+ * heap_prune_page() uses vacrel->vistest for visibility (primarily for
+ * compatibility with on-access pruning, but also because it allows to
+ * prune more). vacrel->vistest is always at least as aggressive as the
+ * limits vacuum_set_xid_limits() computes because ComputeXidHorizons()
+ * (via vacuum_set_xid_limits() ->GetOldestNonRemovableTransactionId())
+ * ensures the approximate horizons are always at least as aggressive as
+ * the precise horizons.
+ */
+ vacrel->vistest = GlobalVisTestFor(vacrel->rel);
+}
+
/*
* lazy_vacuum_all_indexes() -- Main entry for index vacuuming
*
--
2.34.0
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To: pgsql-bugs@postgresql.org
Cc: andres@anarazel.de
Subject: Re: [PATCH v4 4/6] wip: vacuum: Perform horizon determination just before starting scan.
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