elasticsearch之聚合函数

李玉志 2020-02-02

准备数据

PUT zhifou/doc/1
{
  "name":"顾老二",
  "age":30,
  "from": "gu",
  "desc": "皮肤黑、武器长、性格直",
  "tags": ["黑", "长", "直"]
}

PUT zhifou/doc/2
{
  "name":"大娘子",
  "age":18,
  "from":"sheng",
  "desc":"肤白貌美,娇憨可爱",
  "tags":["白", "富","美"]
}

PUT zhifou/doc/3
{
  "name":"龙套偏房",
  "age":22,
  "from":"gu",
  "desc":"mmp,没怎么看,不知道怎么形容",
  "tags":["造数据", "真","难"]
}


PUT zhifou/doc/4
{
  "name":"石头",
  "age":29,
  "from":"gu",
  "desc":"粗中有细,狐假虎威",
  "tags":["粗", "大","猛"]
}

PUT zhifou/doc/5
{
  "name":"魏行首",
  "age":25,
  "from":"广云台",
  "desc":"仿佛兮若轻云之蔽月,飘飘兮若流风之回雪,mmp,最后竟然没有嫁给顾老二!",
  "tags":["闭月","羞花"]
}

avg

需求: 查询 from 是 gu 的 人的平均年龄。

GET zhifou/doc/_search
{
  "query": {
    "match": {
      "from": "gu"
    }
  },
  "aggs": {
    "my_avg": {
      "avg": {
        "field": "age"
      }
    }
  },
  "_source": ["name", "age"]
}

如果我们只想看 平均值 my_avg 的结果怎么做?

利用size

GET zhifou/doc/_search
{
  "query": {
    "match": {
      "from": "gu"
    }
  },
  "aggs": {
    "my_avg": {
      "avg": {
        "field": "age"
      }
    }
  },
  "size": 0, 
}

max

需求: 查询from 为gu  数据中 最大的age

GET zhifou/doc/_search
{
  "query": {
    "match": {
      "from": "gu"
    }
  },
  "aggs": {
    "my_max": {
      "max": {
        "field": "age"
      }
    }
  },
  "size": 0
}

min

同理上面的max

GET zhifou/doc/_search
{
  "query": {
    "match": {
      "from": "gu"
    }
  },
  "aggs": {
    "my_min": {
      "min": {
        "field": "age"
      }
    }
  },
  "size": 0
}

sum

需求: 查询from为gu 的数据的 age的总和

GET zhifou/doc/_search
{
  "query": {
    "match": {
      "from": "gu"
    }
  },
  "aggs": {
    "my_sum": {
      "sum": {
        "field": "age"
      }
    }
  },
  "size": 0
}

分组查询

需求: 查询所有人的年龄段,并且按照15-20,20--25,25-30 分组, 并计算每组的平均年龄

GET zhifou/doc/_search
{
  "size": 0, 
  "query": {
    "match_all": {}
  },
  "aggs": {
    "age_group": {
      "range": {
        "field": "age",
        "ranges": [
          {
            "from": 15,
            "to": 20
          },
          {
            "from": 20,
            "to": 25
          },
          {
            "from": 25,
            "to": 30
          }
        ]
      },
      "aggs": {
        "my_avg": {
          "avg": {
            "field": "age"
          }
        }
      }
    }
  }
}

注意:聚合函数的使用,一定是先查出结果,然后对结果使用聚合函数做处理

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