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From: Mark Lewis <mark.lewis@mir3.com>
To: Greg Stark <gsstark@mit.edu>
Cc: Markus Schaber <schabi@logix-tt.com>
Cc: pgsql-performance@postgresql.org
Cc: pgsql-hackers@postgresql.org
Subject: Re: qsort again (was Re: [PERFORM] Strange Create Index
Date: Thu, 16 Feb 2006 15:23:09 -0800
Message-ID: <1140132189.9076.261.camel@archimedes> (raw)
In-Reply-To: <871wy23okp.fsf@stark.xeocode.com>
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>
	<43F481CD.2010509@logix-tt.com>
	<43F4A7D8.4050907@modgraph-usa.com>
	<29277.1140110108@sss.pgh.pa.us>
	<1140128256.9076.254.camel@archimedes>
	<43F4FDCC.2000204@logix-tt.com>
	<871wy23okp.fsf@stark.xeocode.com>

On Thu, 2006-02-16 at 17:51 -0500, Greg Stark wrote:
> > > Data types which could probably provide a useful function for f would be
> > > int2, int4, oid, and possibly int8 and text (at least for SQL_ASCII).
> 
> How exactly do you imagine doing this for text?
> 
> I could see doing it for char(n)/varchar(n) where n<=4 in SQL_ASCII though.


In SQL_ASCII, just take the first 4 characters (or 8, if using a 64-bit
sortKey as elsewhere suggested).  The sorting key doesn't need to be a
one-to-one mapping.

-- Mark Lewis



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