-----Original Message----- From: Michael Graham [mailto:mgra...@bloxx.com] Sent: Wednesday, May 04, 2011 11:59 AM To: pgsql-general@postgresql.org Subject: Re: Rearranging simple where clauses
On Wed, 2011-05-04 at 11:49 -0400, Tom Lane wrote: > Well, you failed to show us any concrete examples of the cases you > were looking at, but no I don't think the planner necessarily likes > "all the constants on one side". Most likely the win cases are where > one side of a WHERE-condition operator exactly matches an index, so > you'd need to be looking for places where rearrangement could make > that happen. The reason I never showed you any was because I don't have any I was just curious. But yeah making one side match an index exactly is probably the biggest win. <I.N. I think, it'll be probably the "only" win, not the "biggest" - sometimes big, sometimes small. But, what if there are more than one index based on the column in question? - Which one optimizer is supposed to satisfy by rearranging where clause? Regards, Igor Neyman -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
