Re: effective SELECT from child tables

From: Martijn van Oosterhout <kleptog(at)svana(dot)org>
To: mark(at)mark(dot)mielke(dot)cc
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Ilia Kantor <ilia(at)obnovlenie(dot)ru>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: effective SELECT from child tables
Date: 2005-10-01 14:35:49
Message-ID: 20051001143541.GD13830@svana.org
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On Sat, Oct 01, 2005 at 10:05:22AM -0400, mark(at)mark(dot)mielke(dot)cc wrote:
> It has the 'side or additional benefit' being requested here. The ability
> to filter the child table by some attribute. For example, if the child
> tables are used for partitioning, and the attribute were to keep a date
> range, the field restriction optimization could be used to automatically
> determine the set of tables to use for the date range specified. With
> such a change, it would even work automatically if the date ranges
> overlapped for some reason. Selecting a table name by date is hacky. This
> sort of solution would be a general solution to the problem.

This is what "Constraint Exclusion" does. It uses CHECK constraints on
a table to filter out tables that obviously don't apply to a query.
It's just the the specific case of "tableoid = XXX" is not supported
right now.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.

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