From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mark Liberman <mliberman@mixedsignals.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Why is plan (and performance) different on partitioned table?
Date: Mon, 01 May 2006 22:59:16 -0400
Message-ID: <22530.1146538756@sss.pgh.pa.us> (raw)
In-Reply-To: <9D938282F8C6EE43B748B910386DE93E0138B43C@srvgpimail1.GPI.local>
References: <9D938282F8C6EE43B748B910386DE93E0138B43C@srvgpimail1.GPI.local>
"Mark Liberman" <mliberman@mixedsignals.com> writes:
> I have recently implemented table partitioning in our postgres 8.1 db. =
> Upon analyzing query performance, I have realized that, even when only a =
> single one of the "partitions" has to be scanned, the plan is =
> drastically different, and performs much worse, when I query against the =
> master table (uses merge join), vs. a direct query against the partition =
> directly (uses a hash join). The majority of our queries only access a =
> single partition.
Joins against partitioned tables suck in 8.1 :-(. There is code in CVS
HEAD to improve this, but it didn't get done in time for 8.1.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, mliberman@mixedsignals.com
Subject: Re: Why is plan (and performance) different on partitioned table?
In-Reply-To: <22530.1146538756@sss.pgh.pa.us>
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