From: Itai Zukerman <zukerman@math-hat.com>
To: pgsql-sql@postgresql.org
Subject: Re: count(*), EXISTS, indexes
Date: Fri, 11 Apr 2003 17:32:00 -0400
Message-ID: <87smsora9b.fsf@matt.w80.math-hat.com> (raw)
In-Reply-To: <874r54sr8q.fsf@matt.w80.math-hat.com>
References: <874r54sr8q.fsf@matt.w80.math-hat.com>
> CREATE TABLE A (x int PRIMARY KEY, real v);
> CREATE TABLE B (x int);
>
> I'd like to calculate:
>
> SELECT sum(v) FROM A WHERE EXISTS (SELECT 1 FROM B WHERE A.x=B.x);
This seems to be a reasonably-performing workaround:
SELECT DISTINCT x INTO TEMP C FROM A,B WHERE A.x=B.x;
SELECT sum(v) FROM A,C WHERE A.x=C.x;
--
Itai Zukerman <http://www.math-hat.com/~zukerman/;
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To: pgsql-sql@postgresql.org
Cc: zukerman@math-hat.com
Subject: Re: count(*), EXISTS, indexes
In-Reply-To: <87smsora9b.fsf@matt.w80.math-hat.com>
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