Alexander Korotkov <a.korot...@postgrespro.ru> writes: > On Tue, Jul 2, 2019 at 9:19 PM Nikita Glukhov <n.glu...@postgrespro.ru> wrote: >> We could use commuted "const <-> var" operators for kNN searches, but the >> current implementation requires the existence of "var <-> const" operators, >> and >> order-by-op clauses are rebuilt using them (see match_clause_to_ordering_op() >> at /src/backend/optimizer/path/indxpath.c).
> But probably it's still worth to just add commutator for every <-> > operator and close this question. Yeah, I was just thinking that it was weird not to have the commutator operators, independently of indexing considerations. Seems like a usability thing. regards, tom lane