Re: problem with overloading the "coalesce" function

Emil Rachovsky wrote:
>
> --- Richard Huxton <dev@archonet.com> wrote:
>
>> Emil Rachovsky wrote:
>>>  Hi,
>>> I am trying to overload the "coalesce" function to
>>> accept an integer and a string. Here it is :
>>>
>>> CREATE OR REPLACE FUNCTION "coalesce"(a int4, b
>>> "varchar")
>>>   RETURNS "varchar" AS
>> ...
>>> I have added it to pg_catalog, but still I cant't
>> use
>>> it, I get an error on the second parameter
>> What is the error?
>
> The error is :  invalid input syntax for integer
> That is,it expects an integer as a second parameter,
> since the first is an integer.

Hmm - looking at the source (and \df in psql) it seems the basic problem
is that COALESCE() isn't a function. It has its own code in the parser
and its own expression-node. So - your function never gets called
because the parser sees coalesce() and doesn't build a function - it
builds a coalesce-expression.

It should work fine if you rename your function of course.

HTH
--
   Richard Huxton
   Archonet Ltd