From f51ead09df19f0a074c07657b7de8dba0f3050d6 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 30 Jul 2014 14:41:35 -0400
Subject: [PATCH] Avoid wholesale autovacuuming when autovacuum is nominally
off.
When autovacuum is nominally off, we will still launch autovac workers
to vacuum tables that are at risk of XID wraparound. But after we'd done
that, an autovac worker would proceed to autovacuum every table in the
targeted database, if they meet the usual thresholds for autovacuuming.
This is at best pretty unexpected; at worst it delays response to the
wraparound threat. Fix it so that if autovacuum is nominally off, we
*only* do forced vacuums and not any other work.
Per gripe from Andrey Zhidenkov. This has been like this all along,
so back-patch to all supported branches.
---
src/backend/postmaster/autovacuum.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index b53cfdbf6d..c240d2444c 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -2711,14 +2711,21 @@ relation_needs_vacanalyze(Oid relid,
*wraparound = force_vacuum;
/* User disabled it in pg_class.reloptions? (But ignore if at risk) */
- if (!force_vacuum && !av_enabled)
+ if (!av_enabled && !force_vacuum)
{
*doanalyze = false;
*dovacuum = false;
return;
}
- if (PointerIsValid(tabentry))
+ /*
+ * If we found the table in the stats hash, and autovacuum is currently
+ * enabled, make a threshold-based decision whether to vacuum and/or
+ * analyze. If autovacuum is currently disabled, we must be here for
+ * anti-wraparound vacuuming only, so don't vacuum (or analyze) anything
+ * that's not being forced.
+ */
+ if (PointerIsValid(tabentry) && AutoVacuumingActive())
{
reltuples = classForm->reltuples;
vactuples = tabentry->n_dead_tuples;
--
2.49.0