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Date: Tue, 25 Jun 2013 06:20:29 -0700 (PDT)
From: Kevin Grittner <kgrittn@ymail.com>
Reply-To: Kevin Grittner <kgrittn@ymail.com>
Subject: Re: incorrect row estimates for primary key join
To: Ben <midfield@gmail.com>, bricklen <bricklen@gmail.com>
Cc: "pgsql-performance@postgresql.org list" <pgsql-performance@postgresql.org>
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Ben <midfield@gmail.com> wrote:

> PostgreSQL 9.1.1 on x86_64-suse-linux-gnu, compiled by gcc (SUSE Linux) 4=
.6.2, 64-bit

Consider applying the latest bug fixes for 9.1 -- which would leave
you showing 9.1.9.

http://www.postgresql.org/support/versioning/

> default_statistics_target=A0=A0=A0 | 50=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0 | configuration file

Why did you change this from the default of 100?

> effective_cache_size=A0=A0=A0=A0=A0=A0=A0 | 5632MB=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0 | configuration file

How much RAM is on this machine?=A0 What else is running on it?=20
(Normally people set this to 50% to 75% of total RAM.=A0 Lower values
discourage index usage in queries like your example.)

Do you get a different plan if you set cpu_tuple_cost =3D 0.03?=A0 How
about 0.05?=A0 You can set this just for a single connection and run
explain on the query to do a quick check.

--
Kevin Grittner
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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