elasticsearch的bucket_script怎么使用上一级的bucket_path，如果不能使用有什么其他解决方式？

Question

如题目，我的请求json如下：

{
  "size": 0, 
  "aggs": {
    "car_type": {
      "terms": {
        "field": "screenName",
        "size": 10
      },
      "aggs": {
        "active_num": {
          "terms": {
            "field": "activeNum",
            "size": 10
          },
          "aggs": {
            "active_count": {
              "value_count": {
                "field": "activeNum"
              }
            },
            "result" : {
              "bucket_script": {
                "buckets_path": {
                  "count1" : "car_type>all_count",
                  "count2" : "active_count"
            },
                "script": "params.count2/params.count1"
              }
            }
          }
        },
        "all_count": {
          "value_count": {
            "field": "activeNum"
          }
        }
      }
    }
  }
}

我想在result中使用car_type>all_count这样使用的话会报错如下：

No aggregation found for path [car_type>all_count]

找不到这个path，看了官网确实不能这么实用，然后我更换了使用的位置，请求如下：

{
  "size": 0, 
  "aggs": {
    "car_type": {
      "terms": {
        "field": "screenName",
        "size": 10
      },
      "aggs": {
        "active_num": {
          "terms": {
            "field": "activeNum",
            "size": 10
          },
          "aggs": {
            "active_count": {
              "value_count": {
                "field": "activeNum"
              }
            }
          }
        },
        "all_count": {
          "value_count": {
            "field": "activeNum"
          }
        },
        "result" : {
          "bucket_script": {
             "buckets_path": {
                "count1" : "all_count",
                "count2" : "active_num>active_count"
              },
              "script": "params.count2/params.count1"
          }
        }
      }
    }
  }
}

这样的话就有了另一个错，因为active_count的值会有多个，报错如下：

buckets_path must reference either a number value or a single value numeric metric aggregation, got: java.lang.Object[]

我该怎样才能达到我的目的呢？