CREATE OR REPLACE FUNCTION GetPath(in_id integer)
RETURNS integer AS $$
DECLARE id_p integer;
BEGIN
  if in_id >  0  then
     select id_parent
     into id_p
     from doc_tree
     where id=in_id;
     RETURN id_p;
     select GetPath(in_P);
  end if;  
END;
$$ LANGUAGE 'plpgsql';

CREATE OR REPLACE FUNCTION GetPath(integer)
RETURNS setof integer AS $$
DECLARE id_p integer;
BEGIN
  id_p = $ 1 ;
  LOOP
    RETURN NEXT id_p;
    SELECT id_parent INTO id_p from doc_tree where id = id_p;
    IF id_p =  0  OR NOT FOUND THEN
       EXIT;
    END IF;
  END LOOP;
  RETURN;
END;
$$ LANGUAGE 'plpgsql';

CREATE OR REPLACE FUNCTION GetTree(integer)
RETURNS setof integer AS $$
DECLARE id integer;
BEGIN
  id = $ 1 ;
  LOOP
    RETURN NEXT id;
    SELECT id INTO id from doc_tree where id_parent = id;
    IF id =  0  OR NOT FOUND THEN
       EXIT;
    END IF;
  END LOOP;
  RETURN;
END;
$$ LANGUAGE 'plpgsql';

CREATE OR REPLACE FUNCTION GetTree(integer)
RETURNS setof integer AS $$
DECLARE row_id1 doc_tree%ROWTYPE;
DECLARE row_id2 doc_tree%ROWTYPE;
BEGIN
  FOR row_id1 IN SELECT * from doc_tree where id_parent = $ 1  LOOP
   RETURN NEXT row_id1.id;  
   FOR row_id2 IN SELECT * from GetTree(row_id1.id) LOOP
    RETURN NEXT row_id2.id;  
   END LOOP;
  END LOOP;
  RETURN;
END;
$$ LANGUAGE 'plpgsql';

select * from GetTree( 2 );

select g.id ,d.name
from GetTree( 2 ) g, doc_tree d
where g.id = d.id;