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Re: Add pg_stat_autovacuum_priority

Nathan Bossart <nathandbossart@gmail.com>

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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
Date: 2026-04-08T18:18:58Z
Lists: pgsql-hackers 
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

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix double-free in pg_stat_autovacuum_scores.

  2. Add LOG_NEVER error level code.

  3. Add pg_stat_autovacuum_scores system view.

  4. Remove recheck_relation_needs_vacanalyze().

  5. Add elevel parameter to relation_needs_vacanalyze().

  6. Teach relation_needs_vacanalyze() to always compute scores.

  7. Refactor relation_needs_vacanalyze().

  8. Add rudimentary table prioritization to autovacuum.

  9. Fix per-relation memory leakage in autovacuum.

  10. Fix recently-understood problems with handling of XID freezing, particularly