Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: vincent(dot)moreau(at)leroymerlin(dot)fr
Cc: Michael Fuhr <mike(at)fuhr(dot)org>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Execution plan changed after upgrade from 7.3.9 to 8.2.3
Date: 2007-03-13 13:09:45
Message-ID: 20070313130945.GB4490@alvh.no-ip.org
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vincent(dot)moreau(at)leroymerlin(dot)fr wrote:
> I have attached the requested information.
>
> You will see that the query is quite messy and could be easily improved.
> Unfortunately, it came from a third party application and we do not have
> access to the source code.

There are only nested loops and hash joins, while the other plan seems
to be more elaborate -- I wonder if you have disabled bitmap scan, merge
joins, in 8.2? Try a SHOW enable_mergejoin in psql.

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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