Re: Recheck condition

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От Alvaro Herrera
Тема Re: Recheck condition
Дата
Msg-id 20071130125542.GF1837@alvh.no-ip.org
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Ответ на Re: Recheck condition  ("Josh Harrison" <joshques@gmail.com>)
Ответы Re: Recheck condition  ("Josh Harrison" <joshques@gmail.com>)
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Josh Harrison escribió:

> Thanks...
> I have 1 more question in the same line...
>
> *Query1*
> SELECT person_id  FROM person   WHERE (column1=1 AND column2='62')
> INTERSECT
> SELECT person_id  FROM person  WHERE (column1=1 AND column2='189')

Hmm, I think INTERSECT (and EXCEPT) is pretty stupid in Postgres in
general.  Maybe INTERSECT ALL could be a bit faster, because it can
avoid the sort steps.  Make sure you eliminate duplicates if they are a
concern.

--
Alvaro Herrera                 http://www.amazon.com/gp/registry/DXLWNGRJD34J
"[PostgreSQL] is a great group; in my opinion it is THE best open source
development communities in existence anywhere."                (Lamar Owen)

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