SYS_CONNECT_BY_PATHを使用したOracleの累積カウント

SQL Fiddleサンプルデータの試行錯誤だけで、これは期待されるデータを返すクエリです：

SELECT SYS_CONNECT_BY_PATH(firmware_version, '/') path_,
  firmware_version,
  device_count,
  dmc_id,
  charging_group_id,
  IMAGE_PREREQUISITE,
  (SELECT SUM(device_count)
  FROM DM_TEMP_SUMMING_DVC_BY_FW t2
  START WITH t1.firmware_version = t2.firmware_version
        and T1.dmc_id = T2.dmc_id
        and T1.charging_group_id = T2.charging_group_id
  CONNECT BY nocycle PRIOR firmware_version=image_prerequisite and prior dmc_id = dmc_id and prior charging_group_id = charging_group_id
  ) sum_device
FROM DM_TEMP_SUMMING_DVC_BY_FW t1
START WITH image_prerequisite IS NULL
CONNECT BY nocycle PRIOR firmware_version = image_prerequisite
    and prior dmc_id = dmc_id
    and prior charging_group_id = charging_group_id

注： はい、charging_group_id およびdmc_id krokodilkoが上記のコメントで正しく言及しているように、期待される結果にとって非常に重要です。