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help / color / mirror / Atom feedFrom: Nathan Bossart <nathandbossart@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Eisentraut <peter@eisentraut.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@lists.postgresql.org, "Imseih (AWS), Sami" <simseih@amazon.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: allow changing autovacuum_max_workers without restarting
Date: Tue, 29 Apr 2025 12:42:19 -0500
Message-ID: <aBEPe-OHYbnNezTM@nathan> (raw)
In-Reply-To: <1052019.1745947915@sss.pgh.pa.us>
References: <1359669.1736206603@sss.pgh.pa.us>
<Z3yVFfKG_RAh8FgP@nathan>
<1386858.1736220547@sss.pgh.pa.us>
<Z31jI10tLLd6thfu@nathan>
<de722583-4ba4-4063-bc41-e20684978116@eisentraut.org>
<713236.1745846094@sss.pgh.pa.us>
<aA-TlhU2ZoBBAqc-@nathan>
<15005c8c-7676-43b7-a440-787b101cfdf5@eisentraut.org>
<1050120.1745947158@sss.pgh.pa.us>
<1052019.1745947915@sss.pgh.pa.us>
On Tue, Apr 29, 2025 at 01:31:55PM -0400, Tom Lane wrote:
> I wrote:
>> Andres seemed lukewarm about reverting 38da05346 or 6d0154196, so
>> I left it be for the moment. But I still feel the argument is good
>> that "these will do little except confuse future hackers". Barring
>> objection, I'll go revert them.
>
> Actually ... on looking again at 6d0154196 ("Lower default value of
> autovacuum_worker_slots in initdb as needed"), it doesn't look that
> silly. If we're unable to allocate max_connections = 100, turning
> it down while still insisting on 16 AV worker slots doesn't seem
> terribly sane. Maybe we'd choose a formula other than
> "(max_connections / 6)" if we were doing it afresh, but not scaling
> autovacuum_worker_slots at all doesn't seem like the best answer.
Fair point.
> So now I'm inclined to leave that one alone. I'd still revert
> 38da05346, which means the comment added by 6d0154196 needs some minor
> adjustments. But I think we can stick with the "(max_connections /
> 6)" formula --- it will produce 3 with trial_conns = 20, but that's
> enough.
Yup, as long as the lowest possible default is >= the default for
autovacuum_max_workers (3), we're good.
--
nathan
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To: pgsql-hackers@postgresql.org
Cc: nathandbossart@gmail.com, tgl@sss.pgh.pa.us, peter@eisentraut.org, andres@anarazel.de, simseih@amazon.com, pryzby@telsasoft.com
Subject: Re: allow changing autovacuum_max_workers without restarting
In-Reply-To: <aBEPe-OHYbnNezTM@nathan>
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