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From: Jim Nasby <Jim.Nasby@BlueTreble.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: vjoshi@zetainteractive.com
To: Scott Marlowe <scott.marlowe@gmail.com>
To: Varadharajan Mukundan <srinathsmn@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Performance issues
Date: Mon, 16 Mar 2015 14:43:46 -0500
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On 3/13/15 7:12 PM, Tomas Vondra wrote:
> (4) I suspect many of the relations referenced in the views are not
>      actually needed in the query, i.e. the join is performed but
>      then it's just discarded because those columns are not used.
>      Try to simplify the views as much has possible - remove all the
>      tables that are not really necessary to run the query. If two
>      queries need different tables, maybe defining two views is
>      a better approach.

A better alternative with multi-purpose views is to use an outer join 
instead of an inner join. With an outer join if you ultimately don't 
refer to any of the columns in a particular table Postgres will remove 
the table from the query completely.
-- 
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com


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