Richard Guo писал(а) 2024-06-19 16:30:
On Wed, Jun 19, 2024 at 12:49 PM Tom Lane <t...@sss.pgh.pa.us> wrote:
Richard Guo <guofengli...@gmail.com> writes:
> It seems to me that the new operator is somewhat artificial, since it is
> designed to support a mergejoin but lacks a valid commutator. So before
> we proceed to discuss the fix, I'd like to know whether this is a valid
> issue that needs fixing.
I do not think we should add a great deal of complexity or extra
planner cycles to deal with this; but if it can be fixed at low
cost, we should.
I think we can simply verify the validity of commutators for clauses in
the form "inner op outer" when selecting mergejoin/hash clauses. If a
clause lacks a commutator, we should consider it unusable for the given
pair of outer and inner rels. Please see the attached patch.
This seems to be working for my test cases.
--
Best regards,
Alexander Pyhalov,
Postgres Professional
