Re: BUG #17158: Distinct ROW fails with Postgres 14

Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> writes:
> This feature is a requirement for multicolumn path and cycle tracking in
> recursive queries, as well as the search/cycle syntax built on top of
> that, so there is a bit more depending on it than might be at first
> apparent.

Hmm.

> Variant 1 is that we let the type cache *not* report hash support for
> the record type, and let callers fill it in. In the attached patch I've
> only done this for hash_array(), because that's what's needed to get the
> tests to pass, but similar code would be possible for row types, range
> types, etc.

> Variant 2 is that we let the type cache report hash support for the
> record type, like now, and then let callers override it if they have
> other options. This is the second attached patch.

I find variant 1 a bit cleaner, and safer. I'd rather default to
assuming that RECORD doesn't hash, when we don't have enough info
to be sure.

regards, tom lane