Since PostgreSQL 8.4 (which you seem to be running), there are default values for function parameters. If you put your parameter last and provide a default, you can simply omit it from the call:
CREATE OR REPLACE FUNCTION foofunc(_param1 integer
, _param2 date
, _ids int[] DEFAULT '{}')
RETURNS SETOF foobar -- declare return type!
LANGUAGE plpgsql AS
$func$
BEGIN -- required for plpgsql
IF _ids <> '{}'::int[] THEN -- exclude empty array and NULL
RETURN QUERY
SELECT *
FROM foobar
WHERE f1 = _param1
AND f2 = _param2
AND id = ANY(_ids); -- "IN" is not proper syntax for arrays
ELSE
RETURN QUERY
SELECT *
FROM foobar
WHERE f1 = _param1
AND f2 = _param2;
END IF;
END -- required for plpgsql
$func$;
Major points:
-
The keyword
DEFAULT
is used to declare parameter defaults. Short alternative:=
. -
I removed the redundant
param1
from the messy example. -
Since you return
SELECT * FROM foobar
, declare the return type asRETURNS SETOF foobar
instead ofRETURNS SETOF record
. The latter form with anonymous records is very unwieldy, you’d have to provide a column definition list with every call. -
I use an array of integer (
int[]
) as function parameter. Adapted theIF
expression and theWHERE
clause accordingly. -
IF
statements are not available in plain SQL. Has to beLANGUAGE plpgsql
for that.
Call with or without _ids
:
SELECT * FROM foofunc(1, '2012-1-1'::date);
Effectively the same:
SELECT * FROM foofunc(1, '2012-1-1'::date, '{}'::int[]);
You have to make sure the call is unambiguous. If you have another function of the same name and two parameters, Postgres might not know which to pick. Explicit casting (like I demonstrate) narrows it down. Else, untyped string literals work, too, but being explicit never hurts.
Call from within another function:
CREATE FUNCTION foofuncwrapper(_param1 integer, _param2 date)
RETURNS SETOF foobar
LANGUAGE plgpsql AS
$func$
DECLARE
_ids int[] := '{1,2,3}';
BEGIN
-- whatever
RETURN QUERY
SELECT * FROM foofunc(_param1, _param2, _ids);
END
$func$;