Re: Tightening selection of default sort/group operators

Tom Lane writes:

> What I'm thinking of doing instead is always looking up the "=" operator
> by name, and accepting this as actually being equality if it is marked
> mergejoinable or hashjoinable or has eqsel() as its restriction
> selectivity estimator (oprrest). If we are looking for a "<" operator
> to implement sorting/grouping, then we require "=" to be mergejoinable,
> and we use its lsortop operator (regardless of name).

My first thought is that this seems to be an awefully backwards way to
define operator semantic metadata. I think we either have to flag
operators explicitly ("this is the less-than operator"), or we just
require that < <= = >= > have certain semantics. I could be happy with
both.

--
Peter Eisentraut peter_e(at)gmx(dot)net