Re: POC, WIP: OR-clause support for indexes

On Fri, Oct 4, 2024 at 2:40 PM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> On Fri, Oct 4, 2024 at 2:20 PM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> > On Fri, Oct 4, 2024 at 2:00 PM Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
> > > Yes, transformAExprIn() does the work to coerce all the expressions in
> > > the right part to the same type. Similar logic could be implemented
> > > in match_orclause_to_indexcol(). What worries me is whether it's
> > > quite late stage for this kind of work. transformAExprIn() works
> > > during parse stage, when we need to to resolve types, operators etc.
> > > And we do that once.
> >
> > I agree that it would be a bit awkward. Especially having spent so
> > much time talking about doing this later on, not during parsing. That
> > doesn't mean that it's necessarily the wrong thing to do, though.
>
> True, but we also can't realistically use select_common_type() here. I
> mean, it thinks that we have a ParseState and that there might be
> values with type UNKNOWNOID floating around. By the time we reach the
> planner, neither thing is true. And honestly, it looks to me like
> that's pointing to a deeper problem with your idea.

OK.

To be clear, I don't think that it's essential that we have equivalent
behavior in those cases where the patch applies its transformations. I
have no objections to committing the patch without any handling for
that. It's an important patch, and I really want it to get into 18 in
a form that everybody can live with.

--
Peter Geoghegan