Re: Making the planner more tolerant of implicit/explicit casts

Robert Haas <robertmhaas@gmail.com> writes:
> On Thu, Oct 11, 2012 at 5:59 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I'm reasonably convinced that this is a good fix for HEAD, but am of two
>> minds whether to back-patch it or not.  The problem complained of in
>> bug #7598 may seem a bit narrow, but the real point is that whether you
>> write a cast explicitly or not shouldn't affect planning if the
>> semantics are the same.  This might well be a significant though
>> previously unrecognized performance issue, particularly for people who
>> use varchar columns heavily.

> I have had a few bad experiences with people getting *really* upset
> about plan changes in minor releases, so I would be disinclined to
> back-patch this, even if we're fairly sure that it will be an
> improvement in most/all cases.  It's just not worth the risk of
> discovering otherwise.

I stuck it into 9.2, but not further back.

			regards, tom lane