-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
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 opera
Michael Graham writes:
> I did suspect that the answer would be that the difficulty out ways the
> benefit. But in terms of driving the planner don't we always want to be
> looking to move all the constants to one side of the expression since
> the planner seems to like those?
Well, you failed t
On Wed, 2011-05-04 at 10:49 -0400, Tom Lane wrote:
> Well, it'd require a very large amount of
> type-specific/operator-specific knowledge, and it's not clear what
> would drive the planner towards doing useful rearrangements rather
> than counterproductive ones, and the number of real-world querie
Michael Graham writes:
> I was playing around with some sql in postgres and got to wondering why
> the optimiser can't figure out that rearranging some expressions can
> result in massive improvements in the queue plan. For example id + 5 <
> 100 compared with id < 100 - 5.
> Is it simply that n
Hi,
I was playing around with some sql in postgres and got to wondering why
the optimiser can't figure out that rearranging some expressions can
result in massive improvements in the queue plan. For example id + 5 <
100 compared with id < 100 - 5.
Is it simply that no one has go around to doing
