| From: | "Guillaume Smet" <guillaume(dot)smet(at)gmail(dot)com> |
|---|---|
| To: | "Alvaro Herrera" <alvherre(at)commandprompt(dot)com> |
| Cc: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "pgsql-hackers list" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Suboptimal plan choice problem with 8.3RC2 |
| Date: | 2008-01-22 22:37:39 |
| Message-ID: | 1d4e0c10801221437w66a55581m18dd41d0a79e0545@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Jan 22, 2008 11:22 PM, Alvaro Herrera <alvherre(at)commandprompt(dot)com> wrote:
> > So I wonder why the stats were so bad... I didn't update the data at
> > all after the initial import. Any idea?
>
> Hmm, perhaps the analyze was done with the default statistic target (10)?
It's set to 30 in the postgresql.conf from the beginning (= at least 3
weeks) and PostgreSQL has been restarted a few times (at least for the
upgrade to RC2) so I don't think it's a configuration problem.
I just set default_statistics_target to 10 and run a few
ANALYZE+EXPLAIN ANALYZE query and the plan is the good one for all the
runs. It's set to 10 on the 8.1 box by the way.
I can't drop/recreate the database at will because the customer is
also testing it but I'll try to find a moment to do it tomorrow.
--
Guillaume
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