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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ron <rjpeace@earthlink.net>
Cc: Martijn van Oosterhout <kleptog@svana.org>
Cc: pgsql-performance@postgresql.org
Cc: pgsql-hackers@postgresql.org
Subject: Re: qsort again (was Re: [PERFORM] Strange Create
Date: Thu, 16 Feb 2006 11:20:23 -0500
Message-ID: <28768.1140106823@sss.pgh.pa.us> (raw)
In-Reply-To: <7.0.1.0.2.20060216100954.035b5ee0@earthlink.net>
References: <43F38867.6010701@gpdnet.co.uk>
	<19510.1140036968@sss.pgh.pa.us>
	<19779.1140038874@sss.pgh.pa.us>
	<43F39E53.1020009@gpdnet.co.uk>
	<20781.1140046109@sss.pgh.pa.us>
	<7.0.1.0.2.20060215194635.03b55da0@earthlink.net>
	<21615.1140052893@sss.pgh.pa.us>
	<7.0.1.0.2.20060215223710.03a7c618@earthlink.net>
	<20060216113522.GA3461@uio.no>
	<7.0.1.0.2.20060216071053.0385a1a8@earthlink.net>
	<20060216144833.GG26127@svana.org>
	<7.0.1.0.2.20060216100954.035b5ee0@earthlink.net>

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

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