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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: 2026-04-08T17:56:09Z
Lists: pgsql-hackers 
On Wed, Apr 08, 2026 at 01:17:45PM -0400, Tom Lane wrote:
> Alexander Lakhin <exclusion@gmail.com> writes:
>> Please look at a new anomaly, I and SQLsmith have discovered:
>> SELECT (SELECT score FROM pg_stat_get_autovacuum_scores() LIMIT 1),
>>      (SELECT score FROM pg_stat_get_autovacuum_scores() LIMIT 1);
>> ERROR:  detected double pfree in PgStat Snapshot 0x5f6fa4d95d50
> 
> Good catch, but you're not the first:
> 
> https://www.postgresql.org/message-id/CAHewXNkJKdwb3D5OnksrdOqzqUnXUEMpDam1TPW0vfUkW%3D7jUw%40mail.gmail.com

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...

-- 
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