Обсуждение: Is there a bug in FOR i IN 1..10 LOOP (8.4.4)?

CREATE FUNCTION test() RETURNS text
    LANGUAGE plpgsql
    AS $$DECLARE
  num_var TEXT;
BEGIN
  FOR i IN 1..10 LOOP
    num_var := num_var || ',' || i;
  END LOOP;
  RETURN num_var;
END;$$;

SELECT test();

returns NULL

What makes you think there is a bug?  What does this function return for
you?  It always helps us to see everything you have seen.

Without taking the time to try it on my system, I'd recommend explictly
converting your index to text:
num_var := num_var || ',' || i::text;

RobR