From: Phillip Smith <phillip.smith@weatherbeeta.com.au>
To: 'Stuart McGraw' <smcg2297@frii.com>
To: pgsql-sql@postgresql.org
Subject: Re: slowness when subselect uses DISTINCT
Date: Thu, 19 Apr 2007 08:43:49 +1000
Message-ID: <002a01c7820b$07ee3010$9b0014ac@wbaus090> (raw)
In-Reply-To: <AKEFJAHAPDBEDKIICNJKMEOHCCAA.smcg2297@frii.com>
May I suggest you post an EXPLAIN ANALYZE to the group for the query you're
having problems with...?
-----Original Message-----
From: pgsql-sql-owner@postgresql.org [mailto:pgsql-sql-owner@postgresql.org]
On Behalf Of Stuart McGraw
Sent: Thursday, 19 April 2007 04:17
To: pgsql-sql@postgresql.org
Subject: [SQL] slowness when subselect uses DISTINCT
I have several times now run into what seems
like similar performance problems with some
of my postgresql queries.
I have a view that runs reasonably quicky.
I use this view in a subselect in another
query and that query too runs reasonably
quicky.
The view returns some unwanted duplicate
rows so I modify it using either DISTINCT
or GROUP BY to eliminate them.
View still runs reasonably quickly.
I use the modified view as a subselect as
above, but now the query runs 2-3 orders
of magnitude more slowly than before.
Before I go through the effort of putting
together a specific and concise test case,
has anyone seen this general pattern and
have an explanation or advice? (PG-8.2.3)
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To: pgsql-sql@postgresql.org
Cc: phillip.smith@weatherbeeta.com.au, smcg2297@frii.com
Subject: Re: slowness when subselect uses DISTINCT
In-Reply-To: <002a01c7820b$07ee3010$9b0014ac@wbaus090>
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