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From: Sami Imseih <[email protected]>
To: Nathan Bossart <[email protected]>
Cc: Robert Treat <[email protected]>
Cc: David Rowley <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: Jeremy Schneider <[email protected]>
Cc: [email protected]
Subject: Re: another autovacuum scheduling thread
Date: Wed, 12 Nov 2025 16:10:22 -0600
Message-ID: <CAA5RZ0uf31FQ41udQGL91sp3GdaLqcbwO103Q-zJQcJowq7fEw@mail.gmail.com> (raw)
In-Reply-To: <aRTpqMleDpoQm9OO@nathan>
References: <CAApHDvoCFQxaQjUncTAtCRFAeANe2tpc-WCkJue=FaXRYOkV=Q@mail.gmail.com>
	<CAA5RZ0sw+9rEaW9taNpRZWvuLYMjRa9iibneGfB2ftNSUHT0Ww@mail.gmail.com>
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	<CAA5RZ0udjEYJupob5tv3286e28bMpajgsy+4nAbxg73YyigZFw@mail.gmail.com>
	<CAApHDvq9ecYSetXUhjMc7E_Jcc7gxxRkA0LosX9PP1-jM_Ak8A@mail.gmail.com>
	<aRNmEPQ18qZlLowV@nathan>
	<CAApHDvrtvMF3_W69hOUr2SnbizjC1jc68_Ca0nPYr=+VUkUkAw@mail.gmail.com>
	<aROY-MUVO_mYTl2f@nathan>
	<CAApHDvpo3YxiaP123vghHL-aLkY2vc-e1scpDSpaTFWz1qVaQA@mail.gmail.com>
	<CABV9wwOcD4RM5Hm0d+=KBK8LyHLtEtF3YZ4ak8V3VvOYV9Z4Tw@mail.gmail.com>
	<aRTpqMleDpoQm9OO@nathan>

> I do think re-prioritization is worth considering, but IMHO we should leave
> it out of phase 1.  I think it's pretty easy to reason about one round of
> prioritization being okay.  The order is completely arbitrary today, so how
> could ordering by vacuum-related criteria make things any worse?

While it’s true that the current table order is arbitrary, that arbitrariness
naturally helps distribute vacuum work across tables of various sizes
at a given time

The proposal now is by design forcing all the top bloated table, that
will require more I/O to vacuum to be vacuumed at the same time,
by all workers. Users may observe this after they upgrade and wonder
why their I/O profile changed and perhaps slowed others non-vacuum
related processing down. They also don't have a knob to go back to
the previous behavior.

Of course, this behavior can and will happen now, but with this
prioritization, we are forcing it.

Is this a concern?

--
Sami Imseih
Amazon Web Services (AWS)





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