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Re: BUG #1916: selection criteria from one outer join

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-bugs(at)postgresql(dot)org>
Subject: Re: BUG #1916: selection criteria from one outer join
Date: 2005-09-28 15:07:11
Message-ID: s33a6b5f.085@gwmta.wicourts.gov (view raw or flat)
Thread:
Lists: pgsql-bugs
I agree that it looks like "overenthusiastic propagation
of implied equalities."  (Nicely put.)  I haven't tested
whether this fails in any other version (we've moved all
our instances to 8.1beta2 to pound it the best we can),
but I see that Klint Gore has reported the test case fails
in 7.4.7 and 8.0.0.
 
Any idea on when a fix might be available, or what
conditions must exist in a query for this failure to occur?
If this is too big to fix in 8.1, we would want to try to
identify vulnerable queries proactively, to work around
it somehow.
 
-Kevin
 
 
>>> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> 09/27/05 11:34 PM >>>
"Kevin Grittner" <kevin(dot)grittner(at)wicourts(dot)gov> writes:
> Obviously, adding an outer join to a query which is already returning rows
> should never reduce the number of rows returned.

I think this is a case of overenthusiastic propagation of implied
equalities.  Do you know offhand if it fails in 8.0.* or earlier
branches?

			regards, tom lane


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Next:From: Tom LaneDate: 2005-09-28 15:12:48
Subject: Re: BUG #1916: selection criteria from one outer join on clause applied to other joins
Previous:From: Tom LaneDate: 2005-09-28 14:36:43
Subject: Re: BUG #1915: ERROR: RETURN cannot have a parameter in function returning void at or near "NULL" at character 148

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