On Wed, Feb 26, 2025 at 3:26 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Richard Guo <guofenglinux@gmail.com> writes:
> > Here is the patch.
> Thanks for that. The code and comment added to
> restriction_is_always_true look good, but I can't help wondering
> whether we don't need the same in restriction_is_always_false.
> Not very sure what a query proving the need for that would
> look like, but leaving it asymmetric feels wrong.
Yeah, I think you are right. The thing here is that we don't have a
reliable way to determine if the input expression of a NullTest is
non-nullable if it's a clone clause. This applies to both
restriction_is_always_true and restriction_is_always_false. So I
think we should add the same check in restriction_is_always_false too.
I'll give it a try to find a query that shows this is necessary.
Thanks
Richard
