ElasticSearch中的Bucket_Aggregation没有得到预期的结果

Question

我正尝试在 Total_volume

的基础上，借助bucket_sort对以下聚合的结果存储桶进行排序

汇总：

 "aggs": {
    "Originrampname": {
      "terms": {
        "field": "OriginRampName.keyword"
      },
      "aggs": {
        "Destinationrampname": {
          "terms": {
            "field": "DestinationRampName.keyword"
          },
          "aggs": {
            "Total_volume": {
              "sum": {
                "script": {
                  "source": "doc['BilledCount'].value+doc['MovedCount'].value+doc['InGatedCount'].value",
                  "lang": "painless"
                }
              }
            },
            "sorting": {
              "bucket_sort": {
                "sort": [
                  {
                    "Total_volume": {
                      "order": "desc"
                    }
                  }
                ]
              }
            }
          }
        }
      }
    }
  }

结果：

{
  "took": 6,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 6,
    "max_score": 0,
    "hits": []
  },
  "aggregations": {
    "Originrampname": {
      "doc_count_error_upper_bound": 0,
      "sum_other_doc_count": 0,
      "buckets": [
        {
          "key": "Albany South",
          "doc_count": 3,
          "Destinationrampname": {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 0,
            "buckets": [
              {
                "key": "Chicago South",
                "doc_count": 3,
                "Total_volume": {
                  "value": 561
                }
              }
            ]
          }
        },
        {
          "key": "Albany Central",
          "doc_count": 2,
          "Destinationrampname": {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 0,
            "buckets": [
              {
                "key": "Chicago South",
                "doc_count": 2,
                "Total_volume": {
                  "value": 1223
                }
              }
            ]
          }
        },
        {
          "key": "Albany You",
          "doc_count": 1,
          "Destinationrampname": {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 0,
            "buckets": [
              {
                "key": "Chicago South",
                "doc_count": 1,
                "Total_volume": {
                  "value": 886
                }
              }
            ]
          }
        }
      ]
    }
  }
}

正如您在这里可以清楚地看到的那样，这些存储桶不是按照我定义的标准进行排序的，即Total Volume（但它们是基于doc_count进行排序的）。您能指出我这里的问题还是我犯的任何错误吗？

谢谢