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In-Reply-To: <aROY-MUVO_mYTl2f@nathan>
From: David Rowley <dgrowleyml@gmail.com>
Date: Wed, 12 Nov 2025 09:26:48 +1300
Message-ID: 
 <CAApHDvpo3YxiaP123vghHL-aLkY2vc-e1scpDSpaTFWz1qVaQA@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>,
	Jeremy Schneider <schneider@ardentperf.com>, pgsql-hackers@postgresql.org
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On Wed, 12 Nov 2025 at 09:13, Nathan Bossart <nathandbossart@gmail.com> wrote:
>
> On Wed, Nov 12, 2025 at 09:03:54AM +1300, David Rowley wrote:
> >      /* when enough time has passed, refresh the list to ensure the
> > scores aren't too out-of-date */
> >     if (time is > lastcheck + autovacuum_naptime * <something>)
> >     {
> >         list_free_deep(tables_to_process);
> >        goto the_top;
> >     }
> > } // end of foreach(cell, tables_to_process)
>
> My concern is that this might add already-processed tables back to the
> list, so a worker might never be able to clear it.  Maybe that's not a real
> problem in practice for some reason, but it does feel like a step too far
> for stage 1, as you said above.

Oh, that's a good point. That's a very valid concern. I guess that
could be fixed with a hashtable of vacuumed tables and skipping tables
that exist in there, but the problem with that is that the table might
genuinely need to be vacuumed again. It's a bit tricky to know when a
2nd vacuum is a legit requirement and when it's not. Figuring that out
might me more logic that this code wants to know about.

David