This is not purely supported by PostgreSQL (as far as I know), you can get results combined if they return the same row type. You can do that either through a UNION ALL or a function like following-
CREATE FUNCTION test()
RETURNS SETOF first_table AS
$func$
BEGIN
RETURN QUERY
SELECT * FROM first_table;
RETURN QUERY
SELECT * FROM second_table;
END
Reference:
http://stackoverflow.com/a/7748232[
^]
hope, it helps ;)