hum thanks a lot for the quick answer, if is not abuse of your patience
what is the best alternative to the LEFT OUTER JOINS? RC On Wed, Jul 1, 2009 at 6:12 PM, Mike Ivanov <mi...@activestate.com> wrote: > > Merge Join (cost=111885.70..319492.88 rows=13016048 width=620) > > The outermost merge join has to go through 13 million rows. If you remove > "distinct on (bien.uid)", you'll see that. > > > LEFT outer JOIN ville ON ville.uid = bien.ref_ville > > LEFT outer JOIN freguesia_ville ON freguesia_ville.ref_ville =ville.uid > > This is not enough. You have to add this condition as well: > > AND bien.ref_ville = freguesia_ville.ref_ville > > In other words, when you link three tables by a common field, all three > relationships should be explicitly expressed, otherwise you'll have this > type of explosive row multiplication. > > Although I don't quite understand the purpose of the query, I don't think > you need all those OUTER joins. > > Regards, > Mike > >
