From: | Jeff Frost <jeff(at)frostconsultingllc(dot)com> |
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To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | "'PostgreSQL Performance'" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: query plan worse after analyze |
Date: | 2007-10-06 06:41:05 |
Message-ID: | Pine.LNX.4.64.0710052329150.4620@discord.home.frostconsultingllc.com |
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Lists: | pgsql-performance |
On Sat, 6 Oct 2007, Tom Lane wrote:
> "Jeff Frost" <jeff(at)frostconsultingllc(dot)com> writes:
>> Before analyze it seems to choose Bitmap Heap Scan on episodes
>> current_episode, but after it chooses Index Scan Backward using
>> index_episodes_on_publish_on on episodes current_episode.
>
> Have you tried raising the stats target for "episodes"? Seems like
> the problem is a misestimate of the frequency of matches for
> season_id = something.
Can you set the stats target for an entire table up?
I tried this:
ALTER TABLE episodes ALTER COLUMN season_id SET STATISTICS 1000;
and got the same plan.
And since I had this on a test server, I set the default stats target
up to 100, reran analyze and got the same plan.
Same if I up it to 1000. :-(
--
Jeff Frost, Owner <jeff(at)frostconsultingllc(dot)com>
Frost Consulting, LLC http://www.frostconsultingllc.com/
Phone: 650-780-7908 FAX: 650-649-1954
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