From: Michael Fuhr <mike@fuhr.org>
To: NbForYou <nbforyou@hotmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Process Time X200
Date: Fri, 10 Mar 2006 01:59:43 -0700
Message-ID: <20060310085943.GA8913@winnie.fuhr.org> (raw)
In-Reply-To: <BAY107-DAV18040C8CE1ECE56E895A9EDBED0@phx.gbl>
References: <BAY107-DAV18040C8CE1ECE56E895A9EDBED0@phx.gbl>
On Fri, Mar 10, 2006 at 08:11:44AM +0100, NbForYou wrote:
> As you can see the query isn't useful anymore because of the
> processtime. Please Also notice that both systems use a different
> query plan.
> Also on the webhost we have a loop of 162409 (403 rows * 403 rows).
> Both systems also use a different postgresql version. But I cannot
> believe that the performance difference between 1 version could be
> this big regarding self outer join queries!
What versions are both servers? I'd guess that the webhost is using
7.3 or earlier and you're using 7.4 or later. I created a table
like yours, populated it with test data, and ran your query on
several versions of PostgreSQL. I saw the same horrible plan on
7.3 and the same good plan on later versions. The 7.4 Release Notes
do mention improvements in query planning; apparently one of those
improvements is making the difference.
--
Michael Fuhr
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To: pgsql-performance@postgresql.org
Cc: mike@fuhr.org, nbforyou@hotmail.com
Subject: Re: Process Time X200
In-Reply-To: <20060310085943.GA8913@winnie.fuhr.org>
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