Group By 的 Elasticsearch 聚合然后获取最大日期的字段平均值

Question

我正在尝试在 Elasticsearch 中构建一个查询，它将执行以下操作：
a) 按字段分组（即department_name）
b) 获取最大日期的文档(即record_date)
c) 计算剩余文档字段的平均值(即risk_index_value).

如果我的描述没有那么有用，我已经设法构建了下面的查询：

{
   "size":0,
       "query" : {
        "match": {
          "record_date": "2021-04-08"
        }
    },
   "aggs":{
      "assets":{
         "terms":{
            "field":"department_name",
            "size":10000
         },
         "aggs":{
            "risk_avg":{
               "avg":{
                  "field":"risk_index_value"
               }
            }
         }
      }
   }
}

此查询在业务逻辑方面完全符合我的要求，但我需要以某种方式始终获取最大日期而不为其提供值。有没有办法做到这一点？我需要使用 REST 高级弹性客户端来执行此操作，但即使是原始查询也会非常有用。提前致谢！

编辑：我将添加一些文档示例，以便我的请求更有意义。

假设我们有 11 个文档：

department_name: A
risk_index_value: 10
record_date: 2021-04-28

department_name: A
risk_index_value: 30
record_date: 2021-04-28

department_name: A
risk_index_value: 20
record_date: 2021-04-28

department_name: A
risk_index_value: 100
record_date: 2021-04-20

department_name: A
risk_index_value: 80
record_date: 2021-04-20

department_name: B
risk_index_value: 240
record_date: 2021-04-28

department_name: B
risk_index_value: 220
record_date: 2021-04-28

department_name: B
risk_index_value: 200
record_date: 2021-04-28

department_name: B
risk_index_value: 100
record_date: 2021-04-20

department_name: B
risk_index_value: 90
record_date: 2021-04-20

department_name: C
risk_index_value: 45
record_date: 2021-04-28

所以在下面的数据中，我需要的查询 return 类似于：

department: A
risk_index_avg: 30
record_date: 2021-04-28

department: B
risk_index_avg: 220
record_date: 2021-04-28

department: C
risk_index_avg: 45
record_date: 2021-04-28

希望对您有所帮助。

Answer 1

根据你的问题我了解到，你想要的是每个部门最新记录日期的平均风险指数。

可以使用术语聚合找到最大值。即;

在必填字段上使用术语聚合
按降序排列术语键"order": { "_key": "desc" }
说 size = 1 只得到一个最高值。 （这将是最大值）

"aggs": {
   "maxKey": {
      "terms": {
         "field": "<field whose max is required>",
         "size": 1,
         "order": {
            "_key": "desc"
          }
       }
   }
}

我想，下面是您要查找的查询。

{
  "size": 0,
  "aggs": {
    "EachDepartment": {
      "terms": {
        "field": "department_name",
        "size": 1000
      },
      "aggs": {
        "MaxRecordDate": {
          "terms": {
            "field": "record_date",
            "size": 1,
            "order": {
              "_key": "desc"
            }
          },
          "aggs": {
            "AvgOfRiskIndex": {
              "avg": {
                "field": "risk_index_value"
              }
            }
          }
        }
      }
    }
  }
}

我尝试使用您提供的示例数据执行此操作并得到以下响应。

{
  "aggregations" : {
    "EachDepartment" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : "A",
          "doc_count" : 5,
          "MaxRecordDate" : {
            "doc_count_error_upper_bound" : 0,
            "sum_other_doc_count" : 2,
            "buckets" : [
              {
                "key" : 1619568000000,
                "key_as_string" : "2021-04-28 00:00:00",
                "doc_count" : 3,
                "AvgOfRiskIndex" : {
                  "value" : 20.0
                }
              }
            ]
          }
        },
        {
          "key" : "B",
          "doc_count" : 5,
          "MaxRecordDate" : {
            "doc_count_error_upper_bound" : 0,
            "sum_other_doc_count" : 2,
            "buckets" : [
              {
                "key" : 1619568000000,
                "key_as_string" : "2021-04-28 00:00:00",
                "doc_count" : 3,
                "AvgOfRiskIndex" : {
                  "value" : 220.0
                }
              }
            ]
          }
        },
        {
          "key" : "C",
          "doc_count" : 1,
          "MaxRecordDate" : {
            "doc_count_error_upper_bound" : 0,
            "sum_other_doc_count" : 0,
            "buckets" : [
              {
                "key" : 1619568000000,
                "key_as_string" : "2021-04-28 00:00:00",
                "doc_count" : 1,
                "AvgOfRiskIndex" : {
                  "value" : 45.0
                }
              }
            ]
          }
        }
      ]
    }
  }
}

我希望这能回答你的问题。

编辑：添加了 RestHighLevelClient 代码以创建聚合

AggregationBuilder getAggsBuilder() {
    AggregationBuilder departmentAggs = AggregationBuilders.terms("eachDepartments")
                .field("department_name")
                .size(1000);
    AggregationBuilder maxRecordDateAgg = AggregationBuilders.terms("maxRecordDate")
                .field("record_date")
                .size(1)
                .order(BucketOrder.key(false));
    AggregationBuilder avgRiskIndexAgg = AggregationBuilders.avg("avgRiskIndex")
                .field("risk_index_value");

// add avgRiskIndexAgg to maxRecordDate
    maxRecordDateAgg.subAggregation(avgRiskIndexAgg);

//add maxRecordDate to departmentAggs
    departmentAggs.subAggregation(maxRecordDateAgg);
    return departmentAggs;
}

Group By 的 Elasticsearch 聚合然后获取最大日期的字段平均值

Elasticsearch aggregation for Group By then get Avg of field for Max date

elasticsearch

elasticsearch-aggregation

elasticsearch-dsl

可以使用术语聚合找到最大值。即;