Re: How to push predicate down

salah jubeh <s_jubeh@yahoo.com> writes:
> Sorry,� The scenario, that I posted was not correct. I have traced it and the union was not the problem, As I said
thequery excusion plan is over 5000 line. I have created a scenario which similar to the scenario causes the problem I
have. 

> [ query uses EXCEPT not UNION ]

Hmm.  The code explicitly won't push conditions down through an EXCEPT:

 * 3. If the subquery contains EXCEPT or EXCEPT ALL set ops we cannot push
 * quals into it, because that could change the results.

I remember coming to the conclusion that this is safe for
UNION/INTERSECT but not EXCEPT, but right at the moment I'm not sure why
I thought that --- it seems like a qual that suppresses specific rows
should suppress all matching copies.

            regards, tom lane