Re: [PATCH] pg_sleep(interval)

On 8/16/13 3:35 PM, Robert Haas wrote:
> On Fri, Aug 16, 2013 at 2:57 PM, Greg Stark <stark@mit.edu> wrote:
>> Except there are no data types that can be cast to both double and
>> interval currently.
> 
> That, unfortunately, is not sufficient to avoid a problem.
> 
> rhaas=# create or replace function foo(double precision) returns
> double precision as $$select $1$$ language sql;
> CREATE FUNCTION
> rhaas=# create or replace function foo(interval) returns interval as
> $$select $1$$ language sql;
> CREATE FUNCTION
> rhaas=# select foo('123');
> ERROR:  function foo(unknown) is not unique
> LINE 1: select foo('123');
>                ^
> HINT:  Could not choose a best candidate function. You might need to
> add explicit type casts.

That example can be used as an argument against almost any kind of
overloading.