> if the validator encounters an operator, it looks (by name) for the operator
> in the currently active library to see if it is available, then tries to
> resolve arguments and return values
Yes, that is pretty much correct. Except that there can be several
active libraries, so the validator
I started investigating but didn't get a chance to follow up.
I don't know whether Calcite or Postgres is correct. I suspect the
difference is due to the expression 'comm is null'. Because I don't
know whether GROUPING_ID's behavior is defined if its arguments are
not all columns. But I think the
