Date: Sat, 22 Nov 2025 14:03:54 -0600
From: Nathan Bossart <nathandbossart@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>, Sami Imseih <samimseih@gmail.com>,
	Robert Treat <rob@xzilla.net>,
	Jeremy Schneider <schneider@ardentperf.com>,
	pgsql-hackers@postgresql.org
Subject: Re: another autovacuum scheduling thread
Message-ID: <aSIXKuNtMU33r57X@nathan>
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On Sat, Nov 22, 2025 at 06:28:13AM -0500, Robert Haas wrote:
> What would be an issue is if we
> regressed some kind of common pattern. I admit that's a bit
> speculative and I'm probably being a little paranoid here: doing smart
> things is typically better than doing dumb things, and what we're
> doing right now is dumb.
> 
> On the other hand, once we ship something, we can't pull it back. If
> it causes a problem, someone will call me at 2am and need their system
> fixed right now. If my answer is "well, there are no configuration
> knobs we can change and no way to get back to the old behavior and I'm
> sorry you're having that problem but the only answer is for you to run
> all your VACUUMs manually until two years from now when maybe the
> algorithm will have been improved," it's not going to be a very good
> night. After 15 years at EDB, I've learned that the problem isn't
> being wrong per se; it's having no way to get out from under being
> wrong.

Yeah.  I'm tempted to code up the "weighting factor" GUCs for the next
revision.  As you've noted, those would be useful for tuning and for
reverting back to pre-v19 behavior.  Sure, we might end up with a handful
of retail GUCs that most users don't need, but that's not so terrible.

-- 
nathan