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Re: Occasional Slow Commit

From: Andrew Sullivan <ajs(at)crankycanuck(dot)ca>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Occasional Slow Commit
Date: 2008-10-28 12:47:16
Message-ID: 20081028124716.GE13363@crankycanuck.ca (view raw or flat)
Thread:
Lists: pgsql-performance
On Mon, Oct 27, 2008 at 05:23:37PM -0700, David Rees wrote:

> However, occasionally, processing time will jump up significantly -
> the average processing time is around 20ms with the maximum processing
> time taking 2-4 seconds for a small percentage of transactions. Ouch!
> 
> Turning on statement logging and analyzing the logs of the application
> itself shows that step #4 is the culprit of the vast majority of the
> slow transactions.

My bet is that you're waiting on checkpoints.  Given that you're on
8.3, start fiddling with the checkpoint_completion_target parameter.
0.7 might help.

A

-- 
Andrew Sullivan
ajs(at)commandprompt(dot)com
+1 503 667 4564 x104
http://www.commandprompt.com/

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