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Re: nested select query failing

From: Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>
To: SZUCS Gábor <surrano(at)mailbox(dot)hu>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: nested select query failing
Date: 2003-05-15 14:56:49
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Thu, 15 May 2003, [iso-8859-1] SZUCS Gbor wrote:

> Basically, is it true that IN's can be converted to RIGHT JOIN's quite
> simply? Is it always worth?

I'm not sure you want to convert to an outer join (since you want to throw
away the rows on either side that don't match in an IN).  You also have to
be careful not to get duplicate entries from what was the subquery.

As for whether it's worth doing, in 7.3 and earlier, almost
certainly, in 7.4 almost certainly not. :)

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Subject: Re: [ADMIN] nested query too expensive
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