Date: Fri, 10 Oct 2025 14:44:22 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>,
	Jeremy Schneider <schneider@ardentperf.com>,
	Sami Imseih <samimseih@gmail.com>, pgsql-hackers@postgresql.org
Subject: Re: another autovacuum scheduling thread
Message-ID: <aOliFnwt6433J_Zs@nathan>
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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