| From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
|---|---|
| To: | Josh Harrison <joshques(at)gmail(dot)com> |
| Cc: | Martijn van Oosterhout <kleptog(at)svana(dot)org>, Postgresql General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Recheck condition |
| Date: | 2007-11-30 12:55:42 |
| Message-ID: | 20071130125542.GF1837@alvh.no-ip.org |
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| Thread: | |
| Lists: | pgsql-general |
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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