Call PostgreSQL function with multiple composite output parameters - sql

Question

I'd like to define a function in PostgreSQL 9.1 that takes multiple INOUT parameters of composite types, but I don't know how to call it.
Eg.
CREATE TYPE my_type_a AS (a integer, b float);
CREATE TYPE my_type_b AS (c boolean, d varchar(5));
CREATE FUNCTION my_complex_func(INOUT a my_type_a, INOUT b my_type_b)
RETURNS RECORD
'...'
LANGUAGE plpgsql;
The definition statements execute just fine, but I don't know how to call this function! I tried:
SELECT INTO a, b
a, b FROM my_complex_func(a, b);
but this gives an error:
ERROR: record or row variable cannot be part of multiple-item INTO list

Answer 1

I don't think it has anything to do with your input types, or the number of them.
Don't return a RECORD, return a real composite type (defined with CREATE TYPE).
The error record or row variable cannot be part of multiple-item INTO list is because you're trying to nest a ROW inside another ROW.
This should work:
CREATE TYPE my_type_a AS (a integer, b float);
CREATE TYPE my_type_b AS (c boolean, d varchar(5));
CREATE TYPE ret_type AS (w integer, v boolean);
CREATE FUNCTION my_complex_func(INOUT a my_type_a, INOUT b my_type_b)
RETURNS ret_type as $$
...
$$ LANGUAGE plpgsql;
And then you can do:
SELECT INTO a, b
(x.comp).w, (x.comp).v
FROM (select my_complex_func(j, i) as comp) x;
This concrete example works for me:
create type smelly1 as (a integer, b text);
create type smelly2 as (a boolean, b float);
create type rettype as (w integer, v boolean);
create function foo_func(n smelly1, m smelly2) returns rettype as $$
declare
f_ret rettype;
begin
f_ret.w := n.a;
f_ret.v := m.a;
return f_ret;
end;
$$ language plpgsql;
select (x.comp).w, (x.comp).v from
(select foo_func('(4, hello)'::smelly1, '(true,3.14)'::smelly2) as comp) x;
returns:
w | v
---+---
4 | t
(1 row)