Message-ID: <4C9CEF1E.6000903@ca.afilias.info>
Date: Fri, 24 Sep 2010 14:34:06 -0400
From: Brad Nicholson <bnichols@ca.afilias.info>
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To: pgsql-performance@postgresql.org
Subject: Re: Memory usage - indexes
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  On 10-09-24 01:41 PM, Tobias Brox wrote:
> What do you mean, that you could run regular vacuum less frequently,
> or that the regular vacuum would go faster?

It means that vacuums ran less frequently.  With cron triggered vacuums, 
we estimated when tables needed to be vacuumed, and vacuumed them 
accordingly.  Because of unpredictable shifts in activity, we scheduled 
the vacuums to happen more often than needed.

With autovacuum, we vacuum some of our large tables far less 
frequently.  We have a few large tables that used to get vacuumed every 
other day that now get vacuumed once or twice a month.

The vacuums themselves take longer now as we use the vacuum cost delay 
to control the IO.  That wasn't an option for us when we did manual 
vacuums as that was in 8.1 when vacuums were still treated as long 
running transactions.  Stretching a vacuum out to a few hours  prior to 
8.2 would bloat other tables.

-- 
Brad Nicholson  416-673-4106
Database Administrator, Afilias Canada Corp.