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From: Sami Imseih <[email protected]>
To: Jeremy Schneider <[email protected]>
Cc: Nathan Bossart <[email protected]>
Cc: Robert Treat <[email protected]>
Cc: David Rowley <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: [email protected]
Subject: Re: another autovacuum scheduling thread
Date: Wed, 12 Nov 2025 18:32:12 -0600
Message-ID: <CAA5RZ0ufYr0MPQbGy3zsKf8QQpG5KA5++jSEKGJvjNRKsG+Qzg@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CAA5RZ0uf31FQ41udQGL91sp3GdaLqcbwO103Q-zJQcJowq7fEw@mail.gmail.com>
	<[email protected]>

>
> > On Nov 12, 2025, at 5:10 PM, Sami Imseih <[email protected]> wrote:
> >
> > 
> >>
> >> 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?
>
> It’s still possible to tune the cost delay, the number of autovacuum
> workers, etc - if someone needs to manage too much autovacuum I/O
> concurrency and dialing it back down a little bit. I think that’s sufficient
>

Yes, the need to tune a/v for I/O( lower cost limit, higher cost delay
) will likely be
greater with this change.

--
Sami

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  Subject: Re: another autovacuum scheduling thread
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