plpgsql recursion

Greetings!
I have a table like:

node parent  1       2  2       3  3       4

Since i traverse this table with a recursive function, i want to avoid
infinite recursion loop. I have wrote a function to check that a new record
does not create a circular dependency. The function i wrote is as follow:

CREATE OR REPLACE FUNCTION dba_test(INTEGER,INTEGER) RETURNS TEXT AS ' DECLARE   traversing ALIAS FOR $1;   testing ALIAS FOR $2;   t_rec RECORD; BEGIN   FOR t_rec IN SELECT node,parent FROM dba_test WHERE parent = traversing
LOOP     IF t_rec.node = testing THEN       RETURN ''Circular'';     ELSE       PERFORM dba_test(t_rec.node,testing);     END IF;   END LOOP;   RETURN ''ok'' || testing::text; END;
' LANGUAGE 'plpgsql';

I would use this function BEFORE inserting the new row. But if i try SELECT
dba_test(4,1); i don't have the result i expect. Can i you give me an hint
where am i wrong?

Thank you!

Stefano Vita Finzi
kluge@despammed.com