elasticsearch中doc_count为0，脚本失效？

今天项目中发现了个问题:

{
  "size" : 0,
  "query" : {
    "range" : {
      "requestTime" : {
        "from" : 1487572804559,
        "to" : 1489300804559,
        "format" : "epoch_millis",
        "include_lower" : true,
        "include_upper" : true
      }
    }
  },
  "aggregations" : {
    "events" : {
      "terms" : {
        "field" : "eventId",
        "include" : [ "E_MCRM01" ]
      },
      "aggregations" : {
        "timestamp" : {
          "date_histogram" : { "field" : "@timestamp", "interval" : "1d" },
          "aggregations" : { "hitPunish" : { "terms" : { "field" : "hitPunish", "size" : 0, "order" : { "_count" : "asc" } } }, "hitExps" : { "terms" : { "field" : "hitExps", "size" : 0, "order" : { "_count" : "asc" } } }, "hit" : { "filter" : { "term" : { "hit" : "1" } } }, "hit/traffic" : { "bucket_script" : { "script" : { "inline" : "if(traffic > 0){hit/traffic} else{ 0 }" }, "format" : "#.##", "buckets_path" : { "traffic" : "_count", "hit" : "hit>_count" } } } } }
      }
    }
  }
}

正常结果为：

{

    "key_as_string": "2017-03-06T00:00:00.000Z",
    "key": 1488758400000,
    "doc_count": 12,
    "hit": {
        "doc_count": 0
    },
    "hitPunish": {
        "doc_count_error_upper_bound": 0,
        "sum_other_doc_count": 0,
        "buckets": [ ]
    },
    "hitExps": {
        "doc_count_error_upper_bound": 0,
        "sum_other_doc_count": 0,
        "buckets": [ ]
    },
    "hit/traffic": {
        "value": 0,
        "value_as_string": "0"
    }

}

也出现了意料之外的结果：

{

    "key_as_string": "2017-03-05T00:00:00.000Z",
    "key": 1488672000000,
    "doc_count": 0,
    "hit": {
        "doc_count": 0
    },
    "hitPunish": {
        "doc_count_error_upper_bound": 0,
        "sum_other_doc_count": 0,
        "buckets": [ ]
    },
    "hitExps": {
        "doc_count_error_upper_bound": 0,
        "sum_other_doc_count": 0,
        "buckets": [ ]
    }

}

缺少了

"hit/traffic": {
        "value": 0,
        "value_as_string": "0"
    }

这段，导致了数据结构不一致，给数据处理带了一点麻烦。我尝试了修改脚本那段，无论如何改，还是不出现这段。

我初步怀疑是因为doc_count为0时，脚本就失效了。我在官网上也找了下，没有找到证据支持我这点，先记在这。等以后搞清楚了，再回来修改。