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help / color / mirror / Atom feedFrom: Nathan Bossart <nathandbossart@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>
Cc: Jeremy Schneider <schneider@ardentperf.com>
Cc: Sami Imseih <samimseih@gmail.com>
Cc: pgsql-hackers@postgresql.org
Subject: Re: another autovacuum scheduling thread
Date: Fri, 10 Oct 2025 14:44:22 -0500
Message-ID: <aOliFnwt6433J_Zs@nathan> (raw)
In-Reply-To: <CA+TgmoYC4ShRp8vcyrBjkefSBdFfY1fnUgCvjocN-iq55G-7bA@mail.gmail.com>
References: <20251008164057.6bceb9ed@ardentperf.com>
<CAApHDvo3maZsrZVq=Bur=Z6Gtse4asSEgHU0HzBhhcTfM-AfeA@mail.gmail.com>
<20251008172727.3befd129@ardentperf.com>
<CAApHDvpMEs3rewULyJZ=huT8ZM1C1PboV-G7K7jfGtJSgdx-fA@mail.gmail.com>
<20251008182520.6e05a8b8@ardentperf.com>
<20251008184740.328d45de@ardentperf.com>
<CAApHDvq76BBseUh2cG0=m=8r-j6HF_jrQt16Eszgsxp3bciGQw@mail.gmail.com>
<aOffPCBoQLG5dGd8@nathan>
<aOlC4aDoQcgW8ZpC@nathan>
<CA+TgmoYC4ShRp8vcyrBjkefSBdFfY1fnUgCvjocN-iq55G-7bA@mail.gmail.com>
Thanks for taking a look.
On Fri, Oct 10, 2025 at 02:42:57PM -0400, Robert Haas wrote:
> I think this is a reasonable starting point, although I'm surprised
> that you chose to combine the sub-scores using + rather than Max.
My thinking was that we should consider as many factors as we can in the
score, not just the worst one. If a table has medium bloat and medium
wraparound risk, should it always be lower in priority to something with
large bloat and small wraparound risk? It seems worth exploring. I am
curious why you first thought of Max.
> When I've thought about this problem -- and I can't claim to have
> thought about it very hard -- it's seemed to me that we need to (1)
> somehow normalize everything to somewhat similar units and (2) make
> sure that severe wraparound danger always wins over every other
> consideration, but mild wraparound danger can lose to severe bloat.
Agreed. I need to think about this some more. While I'm optimistic that
we could come up with some sort of normalization framework, I deperately
want to avoid super complicated formulas and GUCs, as those seem like
sure-fire ways of ensuring nothing ever gets committed.
--
nathan
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To: pgsql-hackers@postgresql.org
Cc: nathandbossart@gmail.com, robertmhaas@gmail.com, dgrowleyml@gmail.com, schneider@ardentperf.com, samimseih@gmail.com
Subject: Re: another autovacuum scheduling thread
In-Reply-To: <aOliFnwt6433J_Zs@nathan>
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