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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Gregory Stark <stark@enterprisedb.com>
Cc: Guillaume Smet <guillaume.smet@gmail.com>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Cc: pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] Estimation problem with a LIKE clause containing a /
Date: Fri, 09 Nov 2007 11:33:45 -0500
Message-ID: <11342.1194626025@sss.pgh.pa.us> (raw)
In-Reply-To: <87hcjvpydn.fsf@oxford.xeocode.com>
References: <1d4e0c10711070453q214f089cpd144cbb5193d3c4f@mail.gmail.com>
	<17767.1194453292@sss.pgh.pa.us>
	<11467.1194477248@sss.pgh.pa.us>
	<1d4e0c10711080208n6c9875b4tf5882da3ced18532@mail.gmail.com>
	<27405.1194542548@sss.pgh.pa.us>
	<87prykpc3q.fsf@oxford.xeocode.com>
	<25287.1194568820@sss.pgh.pa.us>
	<28300.1194574114@sss.pgh.pa.us>
	<87hcjvpydn.fsf@oxford.xeocode.com>

Gregory Stark <stark@enterprisedb.com> writes:
> Could we not use the bogus range to calculate the histogram estimate
> but apply the LIKE pattern directly to the most-frequent-values
> instead of applying the bogus range? Or would that be too much code
> re-organization for now?

We have already done that for quite some time.  It won't help
Guillaume's case anyhow: he's got no MCVs, presumably because the field
is unique.

			regards, tom lane



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