global bucket

　　统计单个年龄26岁与所有26岁收入的对比

GET /user/_search
{
  "query":{
    "term":{
      "age":"26"
    }
  },
  "aggs":{
    "single_age_avg_salary":{
      "avg":{
        "field":"salary"
      }
    },
    "all":{
      "global":{},
      "aggs":{
        "all_age_avg_salary":{
          "avg":{
            "field":"salary"
          }
        }
      }
    }
  }
}

结果：

{
  "took" : 53,
  "timed_out" : false,
  "_shards" : {
    "total" : 3,
    "successful" : 3,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "user",
        "_type" : "_doc",
        "_id" : "5",
        "_score" : 1.0,
        "_source" : {
          "username" : "li",
          "userId" : 5,
          "age" : 26,
          "salary" : 25000,
          "birthday" : "2020-06-02"
        }
      },
      {
        "_index" : "user",
        "_type" : "_doc",
        "_id" : "6",
        "_score" : 1.0,
        "_source" : {
          "username" : "jack",
          "userId" : 6,
          "age" : 26,
          "salary" : 35000,
          "birthday" : "2020-06-02"
        }
      }
    ]
  },
  "aggregations" : {
    "all" : {
      "doc_count" : 6,
      "all_age_avg_salary" : {
        "value" : 26666.666666666668
      }
    },
    "single_age_avg_salary" : {
      "value" : 30000.0
    }
  }
}

     global：就是global bucket,即将所有数据纳入聚合的scope，而不管之前的query查询出来的数据。

     一个结果是基于query搜索结果来聚合的; 一个结果是对所有数据执行聚合后的

• single_age_avg_salary：就是针对query搜索结果，执行的，拿到的，就是26岁的平均价格

• all_age_avg_salary：所有年龄的平均价格