WITH Sub_Set_Thresholds AS
            (SELECT 2 Cnt_Min, 4 Cnt_Max, 5 Sum_A_Min, 15 Sum_A_Max, 4 Avg_B_Min, 5  Avg_B_Max from dual)
, Start_Set AS (      SELECT 1 ID, 1 A, 2 B
  FROM DUAL UNION ALL SELECT 2, 3, 4
  FROM DUAL UNION ALL SELECT 3, 5, 6
  FROM DUAL UNION ALL SELECT 4, 7, 8
  FROM DUAL UNION ALL SELECT 5, 9, 0
  FROM DUAL)
, v(path,cnt,sum_a,sum_b,id) as
 (select to_char(id), 1, a, b, id
    from start_set
  union all
  select v.path || ';' || x.id,
         v.cnt + 1,
         v.sum_a + x.a,
         v.sum_b + x.b,
         x.id
    from v, start_set x
   where x.id > v.id
     and v.cnt < (select cnt_max from Sub_Set_Thresholds)
     and v.sum_a + x.a <= (select sum_a_max from Sub_Set_Thresholds)
     and v.sum_b + x.b <=
         (v.cnt + 1) * (select avg_b_max from Sub_Set_Thresholds))
select path sub_set_id, cnt, sum_a, round(sum_b / cnt, 2) avg_b
  from v
 where sum_a >= (select cnt_min from Sub_Set_Thresholds)
   and sum_b >= cnt * (select avg_b_min from Sub_Set_Thresholds)
   and cnt >= (select cnt_min from Sub_Set_Thresholds)