Re: performance regression, 7.2.3 -> 7.3b5 w/ VIEW

From: Tommi Maekitalo <t(dot)maekitalo(at)epgmbh(dot)de>
To: "Ross J(dot) Reedstrom" <reedstrm(at)rice(dot)edu>, Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: performance regression, 7.2.3 -> 7.3b5 w/ VIEW
Date: 2002-11-13 08:28:38
Message-ID: 200211130928.38199.t.maekitalo@epgmbh.de
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Am Mittwoch, 13. November 2002 07:22 schrieb Ross J. Reedstrom:
> Hey Hackers -
...
>
> CREATE VIEW current_modules AS
> SELECT * FROM modules m
> WHERE module_ident =
> (SELECT max(module_ident) FROM modules
> WHERE m.moduleid = moduleid GROUP BY moduleid);
>
...

I just wonder if you really need the GROUP BY. The subselect should return
exactly one row and so max does without GROUP BY:
CREATE VIEW current_modules AS
SELECT * FROM modules m
WHERE module_ident =
(SELECT max(module_ident) FROM modules
WHERE m.moduleid = moduleid);

Tommi

--
Dr. Eckhardt + Partner GmbH
http://www.epgmbh.de

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