From 3ec8576a02b2b06aa214c8f3c2c3303c8a67639f Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Tue, 31 Mar 2020 08:27:54 +0900 Subject: [PATCH] Revert "Skip redundant anti-wraparound vacuums" This reverts commit 2aa6e33, that added a fast path to skip anti-wraparound and non-aggressive autovacuum jobs (these have no sense as anti-wraparound implies aggressive). With a cluster using a high amount of relations with a portion of them being heavily updated, this could cause autovacuum to lock down, with autovacuum workers attempting repeatedly those jobs on the same relations for the same database, that just kept being skipped. This lock down can be solved with a manual VACUUM FREEZE. Justin King has reported one environment where the issue happened, and Julien Rouhaud and I have been able to reproduce it in a second environment. With a very aggressive autovacuum_freeze_max_age, triggering those jobs with pgbench is a matter of minutes, and hitting the lock down is a lot harder (my local tests failed to do that). Note that anti-wraparound and non-aggressive jobs can only be triggered on a subset of shared catalogs: - pg_auth_members - pg_authid - pg_database - pg_replication_origin - pg_shseclabel - pg_subscription - pg_tablespace While the lock down was possible down to v12, the root cause of those jobs is a much older issue, which needs more analysis. Bonus thanks to Andres Freund for the discussion. Reported-by: Justin King Discussion: https://postgr.es/m/CAE39h22zPLrkH17GrkDgAYL3kbjvySYD1io+rtnAUFnaJJVS4g@mail.gmail.com Backpatch-through: 12 --- src/backend/access/heap/vacuumlazy.c | 24 ++++-------------------- 1 file changed, 4 insertions(+), 20 deletions(-) diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c index 8acb8b8eb6..3d4719d53a 100644 --- a/src/backend/access/heap/vacuumlazy.c +++ b/src/backend/access/heap/vacuumlazy.c @@ -255,23 +255,6 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params, if (params->options & VACOPT_DISABLE_PAGE_SKIPPING) aggressive = true; - /* - * Normally the relfrozenxid for an anti-wraparound vacuum will be old - * enough to force an aggressive vacuum. However, a concurrent vacuum - * might have already done this work that the relfrozenxid in relcache has - * been updated. If that happens this vacuum is redundant, so skip it. - */ - if (params->is_wraparound && !aggressive) - { - ereport(DEBUG1, - (errmsg("skipping redundant vacuum to prevent wraparound of table \"%s.%s.%s\"", - get_database_name(MyDatabaseId), - get_namespace_name(RelationGetNamespace(onerel)), - RelationGetRelationName(onerel)))); - pgstat_progress_end_command(); - return; - } - vacrelstats = (LVRelStats *) palloc0(sizeof(LVRelStats)); vacrelstats->old_rel_pages = onerel->rd_rel->relpages; @@ -400,9 +383,10 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params, initStringInfo(&buf); if (params->is_wraparound) { - /* an anti-wraparound vacuum has to be aggressive */ - Assert(aggressive); - msgfmt = _("automatic aggressive vacuum to prevent wraparound of table \"%s.%s.%s\": index scans: %d\n"); + if (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 {