-----Original Message-----
From: Michael Graham [mailto:mgraham@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
satisfyby rearranging where clause?
Regards,
Igor Neyman
