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Re: We probably need autovacuum_max_wraparound_workers

From: Daniel Farina <daniel(at)heroku(dot)com>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: PgHacker <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: We probably need autovacuum_max_wraparound_workers
Date: 2012-06-28 08:25:15
Message-ID: CAAZKuFZT_GhazRyw7=K28mOEe79n8CitwRG0z0QYciHcQ1S7gg@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Wed, Jun 27, 2012 at 7:00 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> I've seen this at two sites now, and my conclusion is that a single
> autovacuum_max_workers isn't sufficient if to cover the case of
> wraparound vacuum.  Nor can we just single-thread the wraparound vacuum
> (i.e. just one worker) since that would hurt users who have thousands of
> small tables.

I have also witnessed very unfortunate un-smooth performance behavior
around wraparound time. It seems like a bit of adaptive response in
terms of allowed autovacuum throughput to number of pages requiring
wraparound vacuuming would be one load off my mind.  Getting slower
and slower gradually with some way to know that autovacuum has decided
it should work harder and harder is better than the brick wall that
can sneak up currently.

Count me as appreciative for improvements in this area.

-- 
fdr

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