Horton
Menu

Re: Add pg_stat_autovacuum_priority

Tom Lane <tgl@sss.pgh.pa.us>

View thread
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nathan Bossart <nathandbossart@gmail.com>
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: 2026-04-08T19:21:38Z
Lists: pgsql-hackers 
Nathan Bossart <nathandbossart@gmail.com> writes:
> On Wed, Apr 08, 2026 at 02:53:20PM -0400, Tom Lane wrote:
>> ... Aside from this problem, the elog's that
>> relation_needs_vacanalyze emits seem 100% inappropriate and misleading
>> when it's being called from the view.

> FWIW that elog() shouldn't be emitting anything from the view, unless
> something is broken.

[ looks again... ]  Oh, you mean because pg_stat_get_autovacuum_scores
passes 0 for elevel instead of any of the valid elevel constants.
Can you say "undocumented cowboy hack"?  I'd be happier if we added
something like "#define LOG_NEVER 0  /* Never emit this message */"
to elog.h and used that.

>> 2. Add a "bool *should_free" parameter, like we have in tuplestores
>> and some other places.  It's on the caller to pfree if should_free
>> gets set, but since we'd have to touch every caller, we'd not miss
>> any.

> This sounds most similar to the "bool *may_free" idea that Andres just
> posted.  IIUC the idea is that callers can free the result if they want,
> but they aren't required to do so.

Hmm, yeah I suppose a caller that doesn't care about leakage could
skip the pfree.  But are there really any of those?  The complaint
that prompted 02502c1bc concerned databases with many many thousands
of relations.

I now realize that what you said upthread about caching the results
might be a bigger problem, ie if the pgstats code does retain all
these values then we'd have a memory bloat problem there.  Maybe
we need a more aggressive API change that includes a way to specify
"don't cache this result".

			regards, tom lane

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