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Re: Automatic optimization of IN clauses via INNER JOIN

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Grzegorz Jaśkiewicz <gryzman(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 15:23:29
Message-ID: 603c8f070912180723s14f374eew466928def9fa6a54@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
2009/12/18 Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>:
> 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.

But not by PostgreSQL, or so I believe.

...Robert

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