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From: Robert Haas <robertmhaas@gmail.com>
Date: Mon, 24 Nov 2025 14:59:33 -0500
Message-ID: 
 <CA+TgmoaAgv5D6u+_4KKqQFGH1n+jsFZ1mFWh+CSGqDUtyBNsXg@mail.gmail.com>
Subject: Re: another autovacuum scheduling thread
To: David Rowley <dgrowleyml@gmail.com>
Cc: Sami Imseih <samimseih@gmail.com>,
 Nathan Bossart <nathandbossart@gmail.com>,
	Robert Treat <rob@xzilla.net>, Jeremy Schneider <schneider@ardentperf.com>,
 pgsql-hackers@postgresql.org
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On Sun, Nov 23, 2025 at 4:55=E2=80=AFAM David Rowley <dgrowleyml@gmail.com>=
 wrote:
> One thing that seems to be getting forgotten again is the "/* Stop
> applying cost limits from this point on */" added in 1e55e7d17 is only
> going to be applied when the table *currently* being vaccumed is over
> the failsafe limit. Without Nathan's patch, the worker might end up
> idling along carefully obeying the cost limits on dozens of other
> tables before it gets around to vacuuming the table that's over the
> failsafe limit, then suddenly drop the cost delay code and rush to get
> the table frozen, before Postgres stops accepting transactions. With
> the patch, Nathan has added some aggressive score scaling, which
> should mean any table over the failsafe limit has the highest score
> and gets attended to first.

Right, so can we use that to construct a specific, concrete scenario
where we can see that the patch ends up delivering better behavior
than we have today? I think it would be a really good to have at least
one fully worked-out case where we can say "look, if you run this
series of commands without the patch, X happens, and with the patch, Y
happens, and look! Y is better."

--=20
Robert Haas
EDB: http://www.enterprisedb.com