user defined type, plpgsql function and NULL

["Bjoern A. Zeeb" <bzeeb-lists@xxxxxxxxxxxxxxxxxx>]

Hi,

let's say one has an user defined data type

CREATE TYPE foobar_t AS ( va varchar(25), vb varchar(4), vc varchar(20), ia integer, ib integer );

and a stored procedure in plgpsql (stripped and sample only):

CREATE OR REPLACE FUNCTION foobar(int, foobar_t, int, varchar) RETURNS INT AS'
DECLARE
        ia              ALIAS FOR $1;
        fbt             ALIAS FOR $2;
        ib              ALIAS FOR $3;
        vc              ALIAS FOR $4;
BEGIN
	...
        IF fbt IS NULL THEN
                RAISE NOTICE ''fbt IS NULL;'';
        ELSE
                RAISE NOTICE ''fbt IS NOT NULL... '';
                IF fbt.va IS NULL THEN
                        RAISE NOTICE ''fbt.va IS NULL;'';
                ELSE
                        RAISE NOTICE ''fbt.va = %'', fbt.va;
                END IF;
		...
	END IF;
	...

        RETURN 0;
END'
        LANGUAGE plpgsql;


If one does a

SELECT foobar(1, NULL, 2, 'end');
NOTICE:  ia = 1
NOTICE:  fbt IS NOT NULL... 
NOTICE:  fbt.va IS NULL;
NOTICE:  fbt.vb IS NULL;
NOTICE:  fbt.vc IS NULL;
NOTICE:  fbt.ia IS NULL;
NOTICE:  fbt.ib IS NULL;
NOTICE:  ib = 2
NOTICE:  vc = end
 foobar 
--------
      0
(1 row)


Note the second argument foobar_t is given as NULL
but $2 IS NOT NULL.

I cannot find anything about this in the docs but I asume
that the single NULL will implicitly set all attributes to NULL?
Is this correct or is it just a "works like that this time but may
change at any time in the future"?


-- 
Greetings
Bjoern A. Zeeb

---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster