Re: Abnormal performance difference between Postgres and MySQL - Mailing list pgsql-performance

From Kevin Grittner
Subject Re: Abnormal performance difference between Postgres and MySQL
Date
Msg-id 49A68692.EE98.0025.0@wicourts.gov
Whole thread Raw
In response to Re: Abnormal performance difference between Postgres and MySQL  (Farhan Husain <russoue@gmail.com>)
Responses Re: Abnormal performance difference between Postgres and MySQL  (Steve Clark <sclark@netwolves.com>)
List pgsql-performance
>>> Farhan Husain <russoue@gmail.com> wrote:
> Thanks a lot Scott! I think that was the problem. I just changed the
> default statistics target to 50 and ran explain. The plan changed
> and I ran explain analyze. Now it takes a fraction of a second!

Yeah, the default of 10 has been too low.  In 8.4 it is being raised
to 100.

> Thanks to all of you who wanted to help me. I would be happy if
> someone does me one last favor. I want to know how these query plans
> are generated and how the parameters you suggested to change affects
> it. If there is any article, paper or book on it please give me the
> name or url.

In terms of tuning in general, you might start with these:

http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server

http://www.postgresql.org/docs/8.3/interactive/runtime-config-query.html

To understand the mechanics of the optimizer you might be best off
downloading the source code and reading through the README files and
comments in the source code.

-Kevin

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