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Message-ID: <47F6D0E5.2050005@gmail.com>
Date: Fri, 04 Apr 2008 18:07:49 -0700
From: paul rivers <rivers.paul@gmail.com>
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To: kevin kempter <kevin@kevinkempterllc.com>
CC: pgsql-performance@postgresql.org
Subject: Re: Partitioned tables - planner wont use indexes
References: <B5B9A348-AC8B-46E2-AA64-2627B2CC069F@kevinkempterllc.com>
In-Reply-To: <B5B9A348-AC8B-46E2-AA64-2627B2CC069F@kevinkempterllc.com>
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kevin kempter wrote:
> Hi List;
>
> Sorry if this is a dupe, my first post never showed up...
>
> I'm having some performance issues with a partitioned table. We have a 
> VERY large table that we've partitioned by day.
>

Unfortunately, that is the defined behavior in this case. From 5.9.6 of 
the manual:

"Constraint exclusion only works when the query's WHERE clause contains 
constants."

[Where the constants are of course your partitioning column(s)]


The best way around this depends mostly on what you're up to. You can 
get the min tablename from the catalogs, or you can keep a table of 
active partitions that your script which drops off old partitions and 
generates new ones can keep updated on the oldest/newest partition 
dates. Or some number of other solutions, whatever you find cleanest for 
your purposes.

Paul