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From: Richard Huxton <dev@archonet.com>
To: Adrian Moisey <adrian@careerjunction.co.za>
Cc: pgsql-performance@postgresql.org
Subject: Re: strange pauses
Date: Wed, 16 Jan 2008 10:50:23 +0000
Message-ID: <478DE16F.50308@archonet.com> (raw)
In-Reply-To: <478DDF83.8070106@careerjunction.co.za>
References: <478DDF83.8070106@careerjunction.co.za>

Adrian Moisey wrote:
> 
> If I tail the logs, I see a steady stream of functions that took longer 
> then 5 seconds.  But every now and then I see nothing for 3 minutes and 
> after that a whole bunch (about 20 - 30) queries all finishing at the 
> same second.

Search this list for references to "checkpoints". If you run 
vmstat/iostat for a bit you should see bursts of disk activity at those 
times.

Counter-intuitively you probably want *more* checkpoints (with less data 
to write out each time), but see the list archives for discussion. Also 
check the manuals for some background info.

HTH

-- 
   Richard Huxton
   Archonet Ltd



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