postgrespro.git / summary / log / commit / refs

commit    dd9ac7d5d80608a640bb82cffb6a805ce84cf112
Author:   Michael Paquier <michael@paquier.xyz>
Date:     Mon Mar 30 23:27:47 2020 +0000

    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 edda82abd0..af322c1f15 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -462,23 +462,6 @@ 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->relnamespace = get_namespace_name(RelationGetNamespace(onerel));
@@ -639,9 +622,10 @@ 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
 			{


[parent: 7c2dbc691c3e]