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To: "David logan" <djlogan2@comcast.net>
cc: pgsql-performance@postgresql.org
Subject: Re: Mystefied at poor performance of a standard query 
In-reply-to: <004001c923be$d8b1f730$8a15e590$@net> 
References: <004001c923be$d8b1f730$8a15e590$@net>
Comments: In-reply-to "David logan" <djlogan2@comcast.net>
	message dated "Wed, 01 Oct 2008 06:11:33 -0600"
Date: Wed, 01 Oct 2008 09:30:12 -0400
Message-ID: <8396.1222867812@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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"David logan" <djlogan2@comcast.net> writes:
> (The question is why this simple select takes me 20 minutes to run...)

What have you got work_mem set to?  The hash join is not going to be
real fast if it has to split the join into multiple batches, so you
want work_mem large enough to hold the whole inner relation.  That would
be at least 20MB in this example, probably quite a bit more after
allowing for per-row overhead in the table.

			regards, tom lane