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To: Jon Nelson <jnelson+pgsql@jamponi.net>
cc: pgsql-performance@postgresql.org
Subject: Re: external sort performance 
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Comments: In-reply-to Jon Nelson <jnelson+pgsql@jamponi.net>
	message dated "Thu, 17 Nov 2011 14:11:30 -0600"
Date: Thu, 17 Nov 2011 19:33:49 -0500
Message-ID: <14905.1321576429@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
X-Archive-Number: 201111/226
X-Sequence-Number: 45737

Jon Nelson <jnelson+pgsql@jamponi.net> writes:
> Is the sorting that is necessary for index creation unable to use a
> hash table? (This is a standard btree index).

Hash aggregation isn't sorting --- it's only useful for grouping.

			regards, tom lane