On Sun, 12 Jan 2003, Gaetano Mendola wrote: > "Bruno Wolff III" <[EMAIL PROTECTED]> wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Gaetano Mendola <[EMAIL PROTECTED]> wrote: > > > Hi all, > > > > > > I have the following query: > > > > > > SELECT count(1) > > > FROM providers p JOIN class_default cd USING (id_provider) > > > JOIN user_data ud USING (id_class) > > > JOIN v_user_traffic ut USING (id_user) > > > WHERE id_user_status in (4,5) AND > > > p.company = 'XXXXX'; > > > > > > is not slow but I notice that if I do explain analyze with the table > > > reordered > > > inside the select in another way the cost change. > > > Using "JOIN" fixes the order that tables are joined in. If you are > > just doing inner joins, then you probably don't want to use the "JOIN" > > keyword. The exception being when there are so many tables being joined > > that you want to manually specify at least some of the join ordering in > > order to help out the planner. > > And where is written this behavior ? Is it SQL standard ?
http://www.postgresql.org/idocs/index.php?explicit-joins.html The standard generally has nothing to say about optimization. ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
