"Oliveiros d'Azevedo Cristina" <oliveiros.cristina@xxxxxxxxxxx> wrote: > What is faster? A JOIN or a WHERE a IN (SELECT ... ) On 8.4 and later an EXISTS or NOT EXISTS will use semi-join or anti-join (respectively). These should usually be much faster than the IN (SELECT DISTINCT ... ) technique. Be careful of the difference in semantics between NOT EXISTS and NOT IN if any of the columns involved in the matching can be null -- they are *not* the same thing. -Kevin -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
