Re: Automatic optimization of IN clauses via INNER JOIN

From: Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Thomas Hamilton <thomashamilton76(at)yahoo(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Automatic optimization of IN clauses via INNER JOIN
Date: 2009-12-18 14:24:00
Message-ID: 2f4958ff0912180624v48f8b23cyf4c218d41f80e145@mail.gmail.com
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On Fri, Dec 18, 2009 at 2:18 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> NOT IN is the only that really kills you as far as optimization is
> concerned.  IN can be transformed to a join.  NOT IN forces a NOT
> (subplan)-type plan, which bites - hard.

in a well designed database (read: not abusing NULLs) - it can be done
with joins too.

--
GJ

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