WITH a(a_date,a_sum) AS (
    VALUES (DATE '2014-10-01', NUMERIC '20'), ('2014-10-01', 30), ('2014-10-02', 40)
), b(b_date,b_sum) AS (
    VALUES (DATE '2014-10-01', NUMERIC '50'), ('2014-10-02', 60), ('2014-10-03', 70)
)
SELECT a.a_date,a.a_sum,b.b_date,b.b_sum
  FROM (
    SELECT a.*, row_number() OVER (PARTITION BY a_date ORDER BY a_sum) dt_id FROM a) a
  FULL JOIN (
    SELECT b.*, row_number() OVER (PARTITION BY b_date ORDER BY b_sum) dt_id FROM b) b
  ON a.a_date=b.b_date
        AND a.dt_id=1
        AND b.dt_id=1
;