Please supply EXPLAIN ANALYZE output. On Sun, Oct 26, 2003 at 12:25:37AM +0300, Yonatan Goraly wrote: > I am in the process of adding PostgreSQL support for an application, in > addition to Oracle and MS SQL. > I am using PostgreSQL version 7.3.2, Red Hat 9.0 on Intel Pentium III board. > > I have a query that generally looks like this: > > SELECT t1.col1, t2.col1 FROM t1, t2 WHERE t1.x=t2.y AND t2.p='string' > AND t2.q=1 > > This query is strikingly slow (about 100 sec when both t1 and t2 has > about 1,200 records, compare with less than 4 sec with MS SQL and Oracle) > > The strange thing is that if I remove one of the last 2 conditions > (doesn't matter which one), I get the same performance like with the > other databases. > Since in this particular case both conditions ( t2.p='string', t2.q=1) > are not required, I can't understand why having both turns the query so > slow. > A query on table t2 alone is fast with or without the 2 conditions. > > I tired several alternatives, this one works pretty well: > > SELECT t1.col1, t2.col1 FROM t1, t2 WHERE t1.x=t2.y AND > EXISTS ( > SELECT * FROM t2 t2a WHERE t2a.p='string' AND t2a.q=1 AND > t2a.y=t2.y ) > > Since the first query is simpler than the second, it seems to me like a bug. > > Please advise > > Yonatan
-- Martijn van Oosterhout <[EMAIL PROTECTED]> http://svana.org/kleptog/ > "All that is needed for the forces of evil to triumph is for enough good > men to do nothing." - Edmond Burke > "The penalty good people pay for not being interested in politics is to be > governed by people worse than themselves." - Plato
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