ES 筆記四十：聚合的作用範圍及排序

• ES 聚合分析的預設作用範圍是query的查詢結果集

• 同時 ES 還支援以下方式改變聚合的作用範圍

  • Filter
  • Post_Filter

  • Global

    # Query
    POST employees/_search
    {
    "size": 0,
    "query": {
    "range": {
    "age": {
    "gte": 20
    }
    }
    },
    "aggs": {
    "jobs": {
    "terms": {
    "field":"job.keyword"
    
    }
    }
    }
    }

Filter

#Filter
POST employees/_search
{
  "size": 0,
  "aggs": {
    "older_person": {
      "filter":{
        "range":{
          "age":{
            "from":35
          }
        }
      },
      "aggs":{
         "jobs":{
           "terms": {
        "field":"job.keyword"
      }
      }
    }},
    "all_jobs": {
      "terms": {
        "field":"job.keyword"

      }
    }
  }
}

Post_Filter

• 是對聚合分析後的文件進行再次過濾
• Size 無需設定為0
• 使用場景
  • 一條語句，獲取聚合資訊 + 獲取符合條件的文件

#Post field. 一條語句，找出所有的job型別。還能找到聚合後符合條件的結果
POST employees/_search
{
  "aggs": {
    "jobs": {
      "terms": {
        "field": "job.keyword"
      }
    }
  },
  "post_filter": {
    "match": {
      "job.keyword": "Dev Manager"
    }
  }
}

Global

#global
POST employees/_search
{
  "size": 0,
  "query": {
    "range": {
      "age": {
        "gte": 40
      }
    }
  },
  "aggs": {
    "jobs": {
      "terms": {
        "field":"job.keyword"

      }
    },

    "all":{
      "global":{},//Golbal，無視query，對全部文件進行統計
      "aggs":{
        "salary_avg":{
          "avg":{
            "field":"salary"
          }
        }
      }
    }
  }
}

排序

• 指定order，按照count和key 排序
  • 預設情況，按照count降序排序
  • 指定size，就能返回相應的桶

    #排序 order
    #count正序 and key倒敘
    POST employees/_search
    {
    "size": 0,
    "query": {
    "range": {
      "age": {
        "gte": 20
      }
    }
    },
    "aggs": {
    "jobs": {
      "terms": {
        "field": "job.keyword",
        "order": [
          {
            "_count": "asc"
          },
          {
            "_key": "desc"
          }
        ]
      }
    }
    }
    }

• 基於子聚合的數值進行排序

  POST employees/_search
  {
  "size": 0,
  "aggs": {
  "jobs": {
    "terms": {
      "field": "job.keyword",
      "order": [
        {
          "avg_salary": "desc"
        }
      ]
    },
    "aggs": {
      "avg_salary": {
        "avg": {
          "field": "salary"
        }
      }
    }
  }
  }
  }

• 使用子聚合，Aggregation name

  POST employees/_search
  {
  "size": 0,
  "aggs": {
  "jobs": {
    "terms": {
      "field": "job.keyword",
      "order": [
        {
          "stats_salary.min": "desc"
        }
      ]
    },
    "aggs": {
      "stats_salary": {
        "stats": {
          "field": "salary"
        }
      }
    }
  }
  }
  }

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