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Re: pg_autovacuum not having enough suction ?

From: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,"Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>,Otto Blomqvist <o(dot)blomqvist(at)secomintl(dot)com>,"pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: pg_autovacuum not having enough suction ?
Date: 2005-03-25 23:17:06
Message-ID: 1111792626.5783.11.camel@jd2.commandprompt.com (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
> > I'm not sure if autovacuum could be taught to do that --- it could
> > perhaps launch a vacuum as soon as it notices a large fraction of the
> > table got deleted, but do we really want to authorize it to launch
> > VACUUM FULL?  It'd be better to issue the vacuum synchronously
> > as part of the batch updating script, I feel.
> 
> I added this to the TODO section for autovacuum:
> 
>         o Do VACUUM FULL if table is nearly empty?

We should never automatically launch a vacuum full. That seems like a
really bad idea.

Sincerely,

Joshua D. Drake


> 
> I don't think autovacuum is every going to be smart enough to recycle
> during the delete, especially since the rows can't be reused until the
> transaction completes.
> 
> One problem with VACUUM FULL would be autovacuum waiting for an
> exclusive lock on the table.  Anyway, it is documented now as a possible
> issue.
> 
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