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From: Markus Schaber <schabi@logix-tt.com>
To: pgsql-performance@postgresql.org
Cc: pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] Big IN() clauses etc : feature proposal
Date: Wed, 10 May 2006 17:59:26 +0200
Message-ID: <44620DDE.1080500@logix-tt.com> (raw)
In-Reply-To: <446206FF.7050603@superlativ.dk>
References: <1147110142.32369.7.camel@archimedes>
	<20060508175013.GY99570@pervasive.com>
	<28288.1147111196@sss.pgh.pa.us>
	<op.s89zl30wcigqcu@apollo13>
	<20060509105214.P90693@vesihiisi.cksoft.de>
	<op.s8916gm6cigqcu@apollo13>
	<758d5e7f0605090943p1bbfdae2p4cb28ba128288316@mail.gmail.com>
	<op.s9amckxhcigqcu@apollo13>
	<4461EAAC.7030105@logix-tt.com>
	<op.s9cayhotcigqcu@apollo13>
	<20060510145551.GB14476@svana.org>
	<446206FF.7050603@superlativ.dk>

Hi, Nils,

Nis Jorgensen wrote:

> It will probably be quite common for the number to depend on the number
> of rows in other tables. Even if this is fairly constant within one db
> (some assumption), it is likely to be different in others using the same
> function definition. Perhaps a better solution would be to cache the
> result of the estimator function.

Sophisticated estimator functions are free to use the pg_statistics
views for their row count estimation.


HTH,
Markus
-- 
Markus Schaber | Logical Tracking&Tracing International AG
Dipl. Inf.     | Software Development GIS

Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org



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