Обсуждение: Set Returning Function problem

Hi, 

I noticed what i think is a weird behaviour with SRFs. When I use them
in a SELECT clause, and the SRF returns no rows, the query returns no
rows too, when I think it should return an a null column. I'm posting an
example below:


test=> CREATE TABLE foo (cod SERIAL, bar TEXT);
NOTICE:  CREATE TABLE will create implicit sequence "foo_cod_seq" for
"serial" column "foo.cod"
CREATE TABLE

test=> 
test=> INSERT INTO foo (bar) VALUES ('asdasd');
INSERT 60702758 1

test=> CREATE OR REPLACE FUNCTION srf_foo(INTEGER)
test-> RETURNS setof foo
test-> AS '
test'>   SELECT * FROM foo WHERE cod = $1;
test'> ' LANGUAGE 'SQL';
CREATE FUNCTION

test=> 
test=> SELECT cod, (srf_foo(cod)).bar
test-> FROM foo;cod |  bar   
-----+--------  1 | asdasd
(1 record)

test=>
test=> SELECT cod, (srf_foo(50)).bar
test-> FROM foo;cod | bar
-----+-----
(0 records)

Thanks in advance,

-- 
+---------------------------------------------------+
|  Alvaro Nunes Melo    Atua Sistemas de Informacao |
| al_nunes@atua.com.br        www.atua.com.br       |
|    UIN - 42722678            (54) 327-1044        |
+---------------------------------------------------+

Alvaro Nunes Melo <al_nunes@atua.com.br> writes:
> I noticed what i think is a weird behaviour with SRFs. When I use them
> in a SELECT clause, and the SRF returns no rows, the query returns no
> rows too, when I think it should return an a null column.

Why would you think that?  The behavior is exactly right as-is.
        regards, tom lane