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Re: Query kills machine.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Stef <svb(at)ucs(dot)co(dot)za>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Query kills machine.
Date: 2004-08-24 15:23:31
Message-ID: 4015.1093361011@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Stef <svb(at)ucs(dot)co(dot)za> writes:
> Reducing sort_mem to 4096 seems to make it run in a reasonable time
> again. Any idea why? The database does a whole lot of huge sorts
> every day, so I thought upping this parameter would help.

Not if you haven't got the RAM to support it :-(

Another thing you might look at is ANALYZEing the tables again after
you've loaded all the new data.  The row-count estimates seem way off
in these plans.  You might need to increase the statistics target,
too, to get better plans.

			regards, tom lane

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