>>>>> "Tomas" == Tomas Berndtsson <tomas@nocrew.org> writes:
Tomas> Laurent Martelli <laurent@aopsys.com> writes: >> I have this query : >> >> select distinct on
(Pictures.PictureID)* from Pictures where >> Pictures.PictureID not in (select distinct PictureID from >> Keywords); >>
>> and I find it a bit slow. Does anybody have suggestions to run >> this faster ? (I have indexes on PictureID on both
Picturesand >> Keywords)
Tomas> Try this instead:
Tomas> select distinct on (Pictures.PictureID) * from Pictures where Tomas> not exists (select distinct PictureID from
Keywordswhere Tomas> Pictures.PictureID=Keywords.PictureID);
Tomas> I've found that it's usually faster, probably because it can Tomas> use indices better.
It is indeed much faster. Thanks to all of you who answered so fast.
--
Laurent Martelli
laurent@aopsys.com http://www.bearteam.org/~laurent/