Re: Resolving polymorphic functions with relateddatatypes

Gregory Stark <stark@enterprisedb.com> writes:
> I think what you're suggesting is making integer and floating point constants
> like 0 and 0.1 be treated as "unknown" or perhaps a different kind of unknown,
> "unknown integral type" and "unknown numeric type".

No, that would be a pretty dangerous way to go about it, because it
would have side-effects on all sorts of queries whether or not they
made any use of polymorphic functions.  Plus, it would only fix the
issue for numeric-group types, but the same thing would come up if
you had, say, NVL(text, varchar).

What I'd be inclined to think about is making
check_generic_type_consistency and related functions allow the
arguments matched to ANYELEMENT to be of different actual types
so long as select_common_type could determine a unique type to
coerce them all to.  It'd take some refactoring (notably, because
select_common_type wants to throw error on failure, and because
there'd have to be a way to pass back the type that was selected
for use later).
        regards, tom lane