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To: Ron <rjpeace@earthlink.net>
cc: Martijn van Oosterhout <kleptog@svana.org>,
	pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org
Subject: Re: qsort again (was Re: [PERFORM] Strange Create 
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Comments: In-reply-to Ron <rjpeace@earthlink.net>
	message dated "Thu, 16 Feb 2006 10:52:48 -0500"
Date: Thu, 16 Feb 2006 11:20:23 -0500
Message-ID: <28768.1140106823@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Ron <rjpeace@earthlink.net> writes:
> Your cost comment basically agrees with mine regarding the cost of 
> random memory accesses.  The good news is that the number of datums 
> to be examined during the pivot choosing process is small enough that 
> the datums can fit into CPU cache while the pointers to them can be 
> assigned to registers: making pivot choosing +very+ fast when done correctly.

This is more or less irrelevant given that comparing the pointers is not
the operation we need to do.

			regards, tom lane