Date: Sun, 13 Jul 2003 14:50:42 -0700
From: Steve Wampler <swampler@noao.edu>
To: pgsql-sql@postgresql.org
Subject: Replacing a simple nested query?
Message-ID: <20030713215042.GA18643@weaver.tuc.noao.edu>
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I've got a simple nested query:

  select * from attributes where id in (select id from
     attributes where (name='obsid') and (value='oid00066'));

that performs abysmally.  I've heard this described as the
'classic WHERE IN' problem.

Is there a better way to obtain the same results?  The inner
select identifies a set of ids (2049 of them, to be exact)
that are then used to locate records that have the same id
(about 30-40K of those, including the aforementioned 2049).

Thanks!
-Steve

-- 
Steve Wampler -- swampler@noao.edu
Quantum materiae materietur marmota monax si marmota
                    monax materiam possit materiari?