On Fri, Jul 10, 2009 at 11:47 AM, Greg Stark<gsstark@xxxxxxx> wrote: > On Fri, Jul 10, 2009 at 6:37 PM, Jeff Davis<pgsql@xxxxxxxxxxx> wrote: >> >> -- foo has a primary key >> SELECT * FROM foo UNION SELECT * FROM foo; >> >> That's logically equivalent to: >> >> SELECT * FROM foo; >> >> But postgresql will add a sort anyway. > > > Well no, it's equivalent to SELECT DISTINCT * FROM foo; And honestly, I'd rather see development effort go into making complex queries run faster (the things like bitmap indexes on disk etc) rather than optimising things that i can optimise myself. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
