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  • ElasticSearch7.3學習(二十七)----聚合概念(bucket和metric)及其示例

    一、兩個核心概念:bucket和metric

    1.1 bucket

    有如下數據

    city name 
    北京 張三 
    北京 李四
    天津 王五
    天津 趙六
    天津 王麻子

    劃分出來兩個bucket,一個是北京bucket,一個是天津bucket

    北京bucket:包含了2個人,張三,李四

    上海bucket:包含了3個人,王五,趙六,王麻子

    1.2 metric

    metric,就是對一個bucket執行的某種聚合分析的操作,比如說求平均值,求最大值,求最小值

    比如下面的一個sql語句

    select count(*) from book group studymodel

    bucket:group by studymodel --> 那些studymodel相同的數據,就會被劃分到一個bucket中

    metric:count(*),對每個bucket中所有的數據,計算一個數量。例如avg(),sum(),max(),min()

    二、聚合示例

    2.1 數據準備

    首先創建book索引

    PUT /book/
    {
      "settings": {
        "number_of_shards": 1,
        "number_of_replicas": 0
      },
      "mappings": {
        "properties": {
          "name": {
            "type": "text",
            "analyzer": "ik_max_word",
            "search_analyzer": "ik_smart"
          },
          "description": {
            "type": "text",
            "analyzer": "ik_max_word",
            "search_analyzer": "ik_smart"
          },
          "studymodel": {
            "type": "keyword"
          },
          "price": {
            "type": "double"
          },
          "timestamp": {
            "type": "date",
            "format": "yyyy-MM-dd HH:mm:ss||yyyy-MM-dd||epoch_millis"
          },
          "pic": {
            "type": "text",
            "index": false
          }
        }
      }
    }

    添加測試數據

    PUT /book/_doc/1
    {
      "name": "Bootstrap開發",
      "description": "Bootstrap是一個非常流行的開發框架。此開發框架可以幫助不擅長css頁面開發的程序人員輕松的實現一個css,不受瀏覽器限制的精美界面css效果。",
      "studymodel": "201002",
      "price": 38.6,
      "timestamp": "2019-08-25 19:11:35",
      "pic": "group1/M00/00/00/wKhlQFs6RCeAY0pHAAJx5ZjNDEM428.jpg",
      "tags": [
        "bootstrap",
        "dev"
      ]
    }
    
    PUT /book/_doc/2
    {
      "name": "java編程思想",
      "description": "java語言是世界第一編程語言,在軟件開發領域使用人數最多。",
      "studymodel": "201001",
      "price": 68.6,
      "timestamp": "2019-08-25 19:11:35",
      "pic": "group1/M00/00/00/wKhlQFs6RCeAY0pHAAJx5ZjNDEM428.jpg",
      "tags": [
        "java",
        "dev"
      ]
    }
    
    PUT /book/_doc/3
    {
      "name": "spring開發基礎",
      "description": "spring 在java領域非常流行,java程序員都在用。",
      "studymodel": "201001",
      "price": 88.6,
      "timestamp": "2019-08-24 19:11:35",
      "pic": "group1/M00/00/00/wKhlQFs6RCeAY0pHAAJx5ZjNDEM428.jpg",
      "tags": [
        "spring",
        "java"
      ]
    }

    2.2 計算每個studymodel下的商品數量

    sql語句: select studymodel,count(*) from book group by studymodel

    "size": 0,   ==>  作用 :只需要聚合的數據,不需要查詢的數據

    GET /book/_search
    {
      "size": 0,
      "query": {
        "match_all": {}
      },
      "aggs": {
        "group_by_model": {
          "terms": {
            "field": "studymodel"
          }
        }
      }
    }

    結果:

    {
      "took" : 2,
      "timed_out" : false,
      "_shards" : {
        "total" : 1,
        "successful" : 1,
        "skipped" : 0,
        "failed" : 0
      },
      "hits" : {
        "total" : {
          "value" : 3,
          "relation" : "eq"
        },
        "max_score" : null,
        "hits" : [ ]
      },
      "aggregations" : {
        "group_by_model" : {
          "doc_count_error_upper_bound" : 0,
          "sum_other_doc_count" : 0,
          "buckets" : [
            {
              "key" : "201001",
              "doc_count" : 2
            },
            {
              "key" : "201002",
              "doc_count" : 1
            }
          ]
        }
      }
    }

    2.3 計算每個tags下的商品數量

    設置字段"fielddata": true,不設置會報錯

    PUT /book/_mapping/
    {
      "properties": {
        "tags": {
          "type": "text",
          "fielddata": true
        }
      }
    }

    查詢

    GET /book/_search
    {
      "size": 0, 
      "query": {
        "match_all": {}
      }, 
      "aggs": {
        "group_by_tags": {
          "terms": { "field": "tags" }
        }
      }
    }

    結果:

    {
      "took" : 2,
      "timed_out" : false,
      "_shards" : {
        "total" : 1,
        "successful" : 1,
        "skipped" : 0,
        "failed" : 0
      },
      "hits" : {
        "total" : {
          "value" : 3,
          "relation" : "eq"
        },
        "max_score" : null,
        "hits" : [ ]
      },
      "aggregations" : {
        "group_by_tags" : {
          "doc_count_error_upper_bound" : 0,
          "sum_other_doc_count" : 0,
          "buckets" : [
            {
              "key" : "dev",
              "doc_count" : 2
            },
            {
              "key" : "java",
              "doc_count" : 2
            },
            {
              "key" : "bootstrap",
              "doc_count" : 1
            },
            {
              "key" : "spring",
              "doc_count" : 1
            }
          ]
        }
      }
    }

    2.4 加上搜索條件,計算每個tags下的商品數量

    GET /book/_search
    {
      "size": 0, 
      "query": {
        "match": {
          "description": "java程序員"
        }
      }, 
      "aggs": {
        "group_by_tags": {
          "terms": { "field": "tags" }
        }
      }
    }

    結果:

    {
      "took" : 70,
      "timed_out" : false,
      "_shards" : {
        "total" : 1,
        "successful" : 1,
        "skipped" : 0,
        "failed" : 0
      },
      "hits" : {
        "total" : {
          "value" : 2,
          "relation" : "eq"
        },
        "max_score" : null,
        "hits" : [ ]
      },
      "aggregations" : {
        "group_by_tags" : {
          "doc_count_error_upper_bound" : 0,
          "sum_other_doc_count" : 0,
          "buckets" : [
            {
              "key" : "java",
              "doc_count" : 2
            },
            {
              "key" : "dev",
              "doc_count" : 1
            },
            {
              "key" : "spring",
              "doc_count" : 1
            }
          ]
        }
      }
    }

    2.5 計算每個tag下的商品的平均價格

    子聚合

    GET /book/_search
    {
      "size": 0,
      "aggs": {
        "group_by_tags": {
          "terms": {
            "field": "tags"
          },
          "aggs": {
            "avg_price": {
              "avg": {
                "field": "price"
              }
            }
          }
        }
      }
    }

    結果:

    {
      "took" : 0,
      "timed_out" : false,
      "_shards" : {
        "total" : 1,
        "successful" : 1,
        "skipped" : 0,
        "failed" : 0
      },
      "hits" : {
        "total" : {
          "value" : 3,
          "relation" : "eq"
        },
        "max_score" : null,
        "hits" : [ ]
      },
      "aggregations" : {
        "group_by_tags" : {
          "doc_count_error_upper_bound" : 0,
          "sum_other_doc_count" : 0,
          "buckets" : [
            {
              "key" : "dev",
              "doc_count" : 2,
              "avg_price" : {
                "value" : 53.599999999999994
              }
            },
            {
              "key" : "java",
              "doc_count" : 2,
              "avg_price" : {
                "value" : 78.6
              }
            },
            {
              "key" : "bootstrap",
              "doc_count" : 1,
              "avg_price" : {
                "value" : 38.6
              }
            },
            {
              "key" : "spring",
              "doc_count" : 1,
              "avg_price" : {
                "value" : 88.6
              }
            }
          ]
        }
      }
    }

    2.6 計算每個tag下的商品的平均價格,按照平均價格降序排序

    小技巧,如果是查詢全部,match_all可省略

    GET /book/_search
    {
      "size": 0,
      "aggs": {
        "group_by_tags": {
          "terms": {
            "field": "tags",
            "order": {
              "avg_price": "desc"
            }
          },
          "aggs": {
            "avg_price": {
              "avg": {
                "field": "price"
              }
            }
          }
        }
      }
    }

    結果:

    {
      "took" : 4,
      "timed_out" : false,
      "_shards" : {
        "total" : 1,
        "successful" : 1,
        "skipped" : 0,
        "failed" : 0
      },
      "hits" : {
        "total" : {
          "value" : 3,
          "relation" : "eq"
        },
        "max_score" : null,
        "hits" : [ ]
      },
      "aggregations" : {
        "group_by_tags" : {
          "doc_count_error_upper_bound" : 0,
          "sum_other_doc_count" : 0,
          "buckets" : [
            {
              "key" : "spring",
              "doc_count" : 1,
              "avg_price" : {
                "value" : 88.6
              }
            },
            {
              "key" : "java",
              "doc_count" : 2,
              "avg_price" : {
                "value" : 78.6
              }
            },
            {
              "key" : "dev",
              "doc_count" : 2,
              "avg_price" : {
                "value" : 53.599999999999994
              }
            },
            {
              "key" : "bootstrap",
              "doc_count" : 1,
              "avg_price" : {
                "value" : 38.6
              }
            }
          ]
        }
      }
    }

    2.7 按照指定的價格范圍區間進行分組,然后在每組內再按照tag進行分組,最后再計算每組的平均價格

    GET /book/_search
    {
      "size": 0,
      "aggs": {
        "group_by_price": {
          "range": {
            "field": "price",
            "ranges": [
              {
                "from": 0,
                "to": 40
              },
              {
                "from": 40,
                "to": 60
              },
              {
                "from": 60,
                "to": 80
              }
            ]
          },
          "aggs": {
            "group_by_tags": {
              "terms": {
                "field": "tags"
              },
              "aggs": {
                "average_price": {
                  "avg": {
                    "field": "price"
                  }
                }
              }
            }
          }
        }
      }
    }

    結果:

    {
      "took" : 5,
      "timed_out" : false,
      "_shards" : {
        "total" : 1,
        "successful" : 1,
        "skipped" : 0,
        "failed" : 0
      },
      "hits" : {
        "total" : {
          "value" : 3,
          "relation" : "eq"
        },
        "max_score" : null,
        "hits" : [ ]
      },
      "aggregations" : {
        "group_by_price" : {
          "buckets" : [
            {
              "key" : "0.0-40.0",
              "from" : 0.0,
              "to" : 40.0,
              "doc_count" : 1,
              "group_by_tags" : {
                "doc_count_error_upper_bound" : 0,
                "sum_other_doc_count" : 0,
                "buckets" : [
                  {
                    "key" : "bootstrap",
                    "doc_count" : 1,
                    "average_price" : {
                      "value" : 38.6
                    }
                  },
                  {
                    "key" : "dev",
                    "doc_count" : 1,
                    "average_price" : {
                      "value" : 38.6
                    }
                  }
                ]
              }
            },
            {
              "key" : "40.0-60.0",
              "from" : 40.0,
              "to" : 60.0,
              "doc_count" : 0,
              "group_by_tags" : {
                "doc_count_error_upper_bound" : 0,
                "sum_other_doc_count" : 0,
                "buckets" : [ ]
              }
            },
            {
              "key" : "60.0-80.0",
              "from" : 60.0,
              "to" : 80.0,
              "doc_count" : 1,
              "group_by_tags" : {
                "doc_count_error_upper_bound" : 0,
                "sum_other_doc_count" : 0,
                "buckets" : [
                  {
                    "key" : "dev",
                    "doc_count" : 1,
                    "average_price" : {
                      "value" : 68.6
                    }
                  },
                  {
                    "key" : "java",
                    "doc_count" : 1,
                    "average_price" : {
                      "value" : 68.6
                    }
                  }
                ]
              }
            }
          ]
        }
      }
    }

     

    posted @ 2022-05-22 19:46  |舊市拾荒|  閱讀(213)  評論(0編輯  收藏  舉報
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