Re: speed of querry?

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От Dawid Kuroczko
Тема Re: speed of querry?
Дата
Msg-id 758d5e7f0504140720754c7750@mail.gmail.com
обсуждение исходный текст
Ответ на Re: speed of querry?  ("Joel Fradkin" <jfradkin@wazagua.com>)
Ответы Re: speed of querry?  ("Joel Fradkin" <jfradkin@wazagua.com>)
Список pgsql-performance
On 4/14/05, Joel Fradkin <jfradkin@wazagua.com> wrote:
> I have done a vacuum and a vacuum analyze.
> I can try again for kicks, but it is not in production so no new records are
> added and vacuum analyze is ran after any mods to the indexes.
>
> I am still pursuing Dell on why the monster box is so much slower then the
> desktop as well.

First thing:  Do something like:
ALTER TABLE tbljobtitle ALTER COLUMN clientnum SET STATISTICS 50;
make it for each column used, make it even higher than 50 for
many-values columns.
THEN make VACUUM ANALYZE;

Then do a query couple of times (EXPLAIN ANALYZE also :)), then do:
SET enable_seqscan = off;
and rerun the query -- if it was significantly faster, you will want to do:
SET enable_seqscan = on;
and tweak:
SET random_page_cost = 2.1;
...and play with values.  When you reach the random_page_cost which
suits your data, you will want to put it into postgresql.conf

I am sorry if it is already known to you. :)  Also, it is a rather simplistic
approach to tuning PostgreSQL but it is worth doing.  Especially the
statistics part. :)

   Regards,
       Dawid

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