Date: Tue, 09 May 2006 18:49:22 +0200
To: "Dawid Kuroczko" <qnex42@gmail.com>
Subject: Re: [HACKERS] Big IN() clauses etc : feature proposal
Cc: "Christian Kratzer" <ck@cksoft.de>, "Tom Lane" <tgl@sss.pgh.pa.us>,
	pgsql-performance@postgresql.org, pgsql-hackers@postgresql.org
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	<20060509105214.P90693@vesihiisi.cksoft.de>
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>> >       SELECT * FROM somewhere WHERE id IN (SELECT id FROM result)

> Well, you can either
>   SELECT * FROM somewhere JOIN (SELECT id FROM result GROUP BY id) AS
> a USING (id);

	It's the same thing (and postgres knows it)

> You might want to use PL to store values, say PLperl, or even C, say:

	I tried.
	The problem is that you need a set-returning function to retrieve the  
values. SRFs don't have rowcount estimates, so the plans suck.

> Should work faster than a in-application solution :)

	Should, but don't, because of what I said above...

	With the version in CVS tip, supprting a fast =ANY( array ), this should  
be doable, though.