| From: | "Sergey Konoplev" <gray(dot)ru(at)gmail(dot)com> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Richard Huxton" <dev(at)archonet(dot)com> |
| Cc: | "pgsql-general(at)postgresql(dot)org >> PG-General Mailing List" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Very slow queries w/ NOT IN preparation (seems like a bug, test case) |
| Date: | 2008-11-12 15:23:16 |
| Message-ID: | c3a7de1f0811120723x3169f747p5de78739b06a4eb3@mail.gmail.com |
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| Lists: | pgsql-general pgsql-hackers |
>> What configure options did you use, what locale/encoding are you using,
>> what nondefault settings have you got in postgresql.conf?
>>
>> regards, tom lane
>
> You are right. I've found the odd thing (that completely drives me
> mad) in postgresql.conf.
>
> You are able to reproduce slow-not-in queries by switching
> constraint_exclusion to on in your postgresql.conf and running my test
> (which is attached to the first message).
>
On more thing:
If you do
EXPLAIN SELECT 1 FROM table1 WHERE table1_id NOT IN (SELECT column1
FROM (VALUES (123),(456),(789),... a lot of IDs here...)_);
it works as fast as with constraint_exclusion turned to off.
--
Regards,
Sergey Konoplev
--
PostgreSQL articles in english & russian
http://gray-hemp.blogspot.com/search/label/postgresql/
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