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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: Nathan Bossart <nathandbossart@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, "Imseih (AWS), Sami" <simseih@amazon.com>, Justin Pryzby <pryzby@telsasoft.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2025-01-06T21:29:37Z
Lists: pgsql-hackers 
Nathan Bossart <nathandbossart@gmail.com> writes:
> Committed.

Unsurprisingly, this has completely broken buildfarm member sawshark:
you added 13 new semaphores to the system's default requirements,
and we only had headroom for about 4 (cf. 38da05346).

Now maybe we should just abandon the notion that we ought to be
able to start up under OpenBSD/NetBSD's tiny default value of SEMMNS.
If so I'd be inclined to go revert 38da05346, at least in HEAD.
But I kind of wonder whether this feature actually brings value
commensurate with causing installation problems on real-world OSes.

			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.