| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | nickf(at)ontko(dot)com |
| Cc: | "Manfred Koizar" <mkoi-pg(at)aon(dot)at>, "Pgsql-Performance(at)Postgresql(dot) Org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Seeking help with a query that takes too long |
| Date: | 2003-11-12 16:10:34 |
| Message-ID: | 9083.1068653434@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
"Nick Fankhauser" <nickf(at)ontko(dot)com> writes:
>> Nick, can you find out why this row count estimation is so far off?
> It's actually correct:
Sure, the 3501 was the "actual". The estimate was 1 row, which was
pretty far off :-(
> Here are the stats:
It looks like you are running with the default statistics target (10).
Try boosting it to 100 or even more for this column (see ALTER TABLE
SET STATISTICS, then re-ANALYZE) and see if the estimate gets better.
I think the major problem is likely here:
> n_distinct | 24215
which is no doubt much too small (do you have an idea of the number
of distinct actor_full_name_uppercase values?)
regards, tom lane
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