On Wed, Oct 9, 2024 at 7:45 AM Richard Guo <guofenglinux@gmail.com> wrote:
>
> On Tue, Oct 8, 2024 at 9:02 PM Ashutosh Bapat
> <ashutosh.bapat.oss@gmail.com> wrote:
> > But I don't see any relation specific information being
> > considered while deciding whether the clause is constant false.
>
> Isn't rel->notnullattnums relation specific information? We need this
> information to decide if a Var cannot be NULL.
I am talking about restriction_is_always_false() being called from
add_base_clause_to_rel(). The later doesn't pass the given relid or
the corresponding rel to the first. So restriction_is_always_false()
is independent of relid passed to add_base_clause_to_rel() and thus
restriction_is_always_false() being called from outside (say caller of
add_base_clause_to_rel()) will have same result for the same
RestrictInfo.
>
> > So may
> > be we should do this processing elsewhere and replace the original
> > clause itself?
>
> I’m not sure about this. Different versions of the same qual clause
> can lead to different conclusions about whether it can be reduced to
> constant-FALSE.
Can you please provide an example?
> I don't think it is possible to replace the original
> clause; we need to do this processing on a version-by-version basis.
>
Either way, each version will be represented by only one RestrictInfo.
Why can't we replace that version instead of creating a new
RestrictInfo?
--
Best Wishes,
Ashutosh Bapat
