From: Gregory Stark <stark@enterprisedb.com>
To: Greg Jaman <gjaman@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Partition table query performance
Date: Thu, 27 Nov 2008 00:48:14 +0000
Message-ID: <8763maouy9.fsf@oxford.xeocode.com> (raw)
In-Reply-To: <b72893ad0811252007h33cf477dx54d5468705facaaa@mail.gmail.com>
References: <b72893ad0811252007h33cf477dx54d5468705facaaa@mail.gmail.com>
"Greg Jaman" <gjaman@gmail.com> writes:
> I have a problem with partitioning and I'm wondering if anyone can provide
> some insight. I'm trying to find the max value of a column across multiple
> partitions. The query against the partition set is quite slow while queries
> against child partitions is very fast!
I'm afraid this is a known problematic use case of Postgres's current
partitioning support. Postgres is not capable of finding the plan which you're
undoubtedly looking for where it uses the same plan as your child table query
iterating over the partitions.
There are several groups working to improve this in different ways but none of
them appear to be on track to be in 8.4 so it will be 8.5 or later before they
appear. Sorry.
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
Ask me about EnterpriseDB's 24x7 Postgres support!
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To: pgsql-performance@postgresql.org
Cc: stark@enterprisedb.com, gjaman@gmail.com
Subject: Re: Partition table query performance
In-Reply-To: <8763maouy9.fsf@oxford.xeocode.com>
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