PostgreSQL: How to DROP FUNCTION IF EXISTS without specifying parameters?
Solution 1:
In Postgres functions can be overloaded, so parameters are necessary to distinguish overloaded functions. To unambiguously identify a function you can put only types of its parameters.
DROP FUNCTION IF EXISTS Foo(INT);
Solution 2:
As of Postgres 10 you can drop functions by name only, as long as the names are unique to their schema.
Example:
drop function if exists Foo;
Documentation here.