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From: David Rowley <dgrowleyml@gmail.com>
Date: Wed, 18 Mar 2026 12:06:34 +1300
Message-ID: 
 <CAApHDvqHXYCb=x0hHeR1e21ksqFNk4q3_zoPk6V-LLu0VL491Q@mail.gmail.com>
Subject: Re: another autovacuum scheduling thread
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Sami Imseih <samimseih@gmail.com>, Robert Haas <robertmhaas@gmail.com>,
	Robert Treat <rob@xzilla.net>, Jeremy Schneider <schneider@ardentperf.com>,
 pgsql-hackers@postgresql.org
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On Fri, 13 Mar 2026 at 08:20, Nathan Bossart <nathandbossart@gmail.com> wrote:
> I'm debating whether I should move forward with committing this [0] for
> v19.  On one hand, I think I've addressed all the latest feedback, and I'm
> not aware of any sustained objections to the approach.  But on the other
> hand, there hasn't been much discussion since November (my fault), and I
> can't quite tell if this patch has enough support.  At the moment, I'm
> leaning towards committing it, but I'm curious what folks think.

I think it would have been better to have done this about 3 months
ago, but I think it's probably still fine to do now. Feature freeze is
still quite a long way from release. I do expect that the most likely
time that someone would find issues with this change would be during
beta or RC, as that's when people would give PostgreSQL production
workloads to try out. During the dev cycle, I expect it's *mostly*
just hackers giving the database toy workloads in a very targeted way
to something specific that they're hacking on.  Anyway, now since
you've added the GUCs to control the weights, there's a way for users
to have some influence, so at least there's an escape hatch.

I think the GUCs are probably a good idea. I expect the most likely
change that people might want to make would be to raise the priority
of analyze over vacuum since that's often much faster to complete. We
know that some workloads are very sensitive to outdated statistics.

On the other hand, we shouldn't be taking adding 5 new autovacuum GUCs
lightly as there are already so many. If we are going to come up with
something better than this in a few years then it could be better to
wait to reduce the pain of having to remove GUCs in the future. I
don't personally have any better ideas, so I'd rather see it go in
than not.

I didn't look at the patch in detail, but noticed that you might want
to add a "See Section N.N.N for more information." to the new GUCs to
link to the text you've added on how they're used.

Do you think it's worth making the call to
list_sort(tables_to_process, TableToProcessComparator) conditional on
a variable set like: sort_required |= (score != 0.0);? I recall that
someone had concerns that the actual sort itself could add overhead.

David