Re: count(*), EXISTS, indexes - Mailing list pgsql-sql

From Itai Zukerman
Subject Re: count(*), EXISTS, indexes
Date
Msg-id 87smsora9b.fsf@matt.w80.math-hat.com
Whole thread Raw
In response to count(*), EXISTS, indexes  (Itai Zukerman <zukerman@math-hat.com>)
Responses SELECT INTO TEMP in Trigger?  (Itai Zukerman <zukerman@math-hat.com>)
Re: count(*), EXISTS, indexes  (Stephan Szabo <sszabo@megazone23.bigpanda.com>)
List pgsql-sql
>   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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