PostgreSQL:obtendo classificação ordinal (índice de linha?) de forma eficiente

CREATE TEMP TABLE tbl (
   id int
 , dollars int
 , dollars_rank int
 , points int
 , points_rank int
 );
INSERT INTO tbl VALUES
 (1, 20, 1, 35, 1)
,(2, 18, 2, 30, 3)
,(3, 10, 3, 33, 2)
,(4, 10, 3, 33, 2);  -- I put a dupe row in to demonstrate ties.

UPDATE tbl
SET    dollars_rank = r.d_rnk
     , points_rank  = r.p_rnk
FROM (
    SELECT id
         , dense_rank() OVER (ORDER BY dollars DESC) AS d_rnk
         , dense_rank() OVER (ORDER BY points DESC)  AS p_rnk
    FROM   tbl
    ) r
WHERE tbl.id = r.id