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Re: allow changing autovacuum_max_workers without restarting

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@lists.postgresql.org, Nathan Bossart <nathandbossart@gmail.com>, "Imseih (AWS), Sami" <simseih@amazon.com>, Justin Pryzby <pryzby@telsasoft.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2025-01-06T22:36:17Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> How about trying the higher setting first in initdb? On any sane system that won't cost anything because it'll succeed with the higher value.

That might be a good compromise.  You'd have to think about how
it should interact with initdb's probes for workable values of
max_connections.  My first thought about that is to have initdb
set autovacuum_worker_slots to max_connections / 8 or thereabouts
as it works down the list of max_connections values to try.  Or
you could do something more complicated, but I don't see a reason
to make it too complex.

			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. Give up on running with NetBSD/OpenBSD's default semaphore settings.

  2. initdb: Do not report default autovacuum_worker_slots.

  3. Lower default value of autovacuum_worker_slots in initdb as needed.

  4. Allow changing autovacuum_max_workers without restarting.

  5. Reserve a PGPROC slot and semaphore for the slotsync worker process.

  6. Make archiver process an auxiliary process.

  7. Correct the formulas for System V IPC parameters SEMMNI and SEMMNS in docs.