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From: Jeremy Schneider <[email protected]>
To: Sami Imseih <[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 18:51:13 -0500
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAA5RZ0uf31FQ41udQGL91sp3GdaLqcbwO103Q-zJQcJowq7fEw@mail.gmail.com>
References: <CAA5RZ0uf31FQ41udQGL91sp3GdaLqcbwO103Q-zJQcJowq7fEw@mail.gmail.com>


> 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

-Jeremy

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