problem with overloading the "coalesce" function
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
$BODY$
begin
if (a is null ) then
return b;
else
return cast(a as varchar(15));
end if;
end
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
ALTER FUNCTION "coalesce"(a int4, b "varchar") OWNER
TO postgres;
I have added it to pg_catalog, but still I cant't use
it, I get an error on the second parameter, apparently
the function gets lost at some point. Any additional
steps I need to complete?
Thanks in advance,
Emil
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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?
--
Richard Huxton
Archonet Ltd
--- 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.
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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
Richard Huxton <dev@archonet.com> writes:
Hmm - looking at the source (and \df in psql) it seems the basic problem
is that COALESCE() isn't a function.
If it were an ordinary function, it couldn't satisfy the property of not
evaluating "unused" arguments ...
regards, tom lane