Date: Wed, 8 Apr 2026 13:18:58 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Alexander Lakhin <exclusion@gmail.com>,
	Sami Imseih <samimseih@gmail.com>,
	Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>,
	Robert Treat <rob@xzilla.net>, satyanarlapuram@gmail.com,
	pgsql-hackers <pgsql-hackers@postgresql.org>, tndrwang@gmail.com
Subject: Re: Add pg_stat_autovacuum_priority
Message-ID: <adacEjlRZco26f0h@nathan>
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On Wed, Apr 08, 2026 at 12:56:09PM -0500, Nathan Bossart wrote:
> Hm.  I can't get excited about checking pgstat_fetch_consistency (as
> proposed in that other report), but I see that commit 02502c1bca added the
> freeing behavior in question.  I wonder if it makes sense to just skip
> freeing when relation_needs_vacanalyze() is called from the view, i.e., not
> an autovacuum worker.  On the other hand, maybe we shouldn't be caching
> entries for a view like this that looks through all tables in the
> database...

Concretely, this is what I'm thinking:

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index bd626a16363..6d4a34257fb 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -3327,7 +3327,15 @@ relation_needs_vacanalyze(Oid relid,
              anltuples, anlthresh, scores->anl,
              scores->xid, scores->mxid);

-    pfree(tabentry);
+    /*
+     * Avoid leaking pgstat entries until the end of autovacuum.  Elsewhere,
+     * we let the commit/abort machinery take care of freeing it.  While
+     * autovacuum workers set stats_fetch_consistency to "none", it might be
+     * set to a different value in other processes, so we can't safely free it
+     * here for them.
+     */
+    if (AmAutoVacuumWorkerProcess())
+        pfree(tabentry);
 }

 /*

-- 
nathan