Jeremy Drake <pgsql(at)jdrake(dot)com> writes:
> I just think it is quite unexpected that the operator < is defined in some
> places and not in others.
Row-wise comparison isn't an operator, it's a syntactic construct.
Consider
(now(), 'foo', 42) < (SELECT timestampcol, textcol, intcol FROM sometable WHERE ...)
There isn't any single operator in the system that implements that.
(And no, orthogonality is not one of the strong points of SQL...)
regards, tom lane