On Tue, Jul 08, 2014 at 11:19:31AM -0400, Tom Lane wrote: > Moshe Jacobson <mo...@neadwerx.com> writes: > > > Seeing that there is only one output column, and that the results are > > grouped by this output column, it seems to me that the optimizer should not > > even look at the rest of the tables. > > The GROUP BY has nothing to do with it, but if all the other tables' join > keys are primary keys (or at least unique), I'd expect the planner to get > rid of the joins. However, I'm not sure whether it works completely when > there are more than join_collapse_limit relations to worry about.
Eliminating JOINs seems orthogonal, at least in theory, to join_collapse_limit. What have I missed here, and how might they have dependencies? Cheers, David. -- David Fetter <da...@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers