Elasticsearch 7.x 【02】

主要內容：7種搜索方式的簡單操作

1、query string search
2、query DSL
3、query filter
4、full-text search
5、phrase search
6、highlight search
7、term query

1、query string search

名稱由來：search參數都是以http請求的query string來附帶的

參數列表

搜索示例：
搜索全部商品

GET /ecommerce/_search

{
  "took" : 11,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 5,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [
      {
        "_index" : "ecommerce",
        "_type" : "_doc",
        "_id" : "SH1w83ABZ60GR8nZv1rN",
        "_score" : null,
        "_source" : {
          "name" : "zhonghua yagao",
          "desc" : "caoben zhiwu",
          "price" : 40,
          "producer" : "zhonghua producer",
          "tags" : [
            "qingxin"
          ]
        },
        "sort" : [
          40
        ]
      }      
    ]
  }
}

字段說明：

took：耗費了幾毫秒
timed_out：是否超時
_shards：分片數量，搜索請求會打到所有的primary shard（或者是它的某個replica shard也可以）
hits.total：查詢結果的數量
hits.max_score：就是document對於一個search的相關度的匹配分數，越相關，就越匹配，分數也高
hits.hits：包含了匹配搜索的document的詳細數據

搜索名爲yagao的商品，並按價格進行降序排列

GET /ecommerce/_search?q=name:yagao&sort=price:desc

小結

適用於臨時的在命令行使用一些工具，比如curl，快速的發出請求，來檢索想要的信息；但是如果查詢請求很複雜，是很難去構建的，在生產環境中，幾乎很少使用query string search

2、query DSL

DSL：Domain Specified Language，特定領域的語言
http request body：請求體，可以用json的格式來構建查詢語法，比較方便，可以構建各種複雜的語法.

查詢示例：

GET /ecommerce/_search
{
  "query": {
    "match_all": {}
  }
}

查詢名稱包含yagao的商品，同時按照價格降序排序

GET /ecommerce/_search
{
  "query": {
    "match": {
      "name": "yagao"
    }
  },
  "sort": [
    {
      "price": "desc"
    }
  ]
}

分頁查詢商品，總共3條商品，假設每頁就顯示1條商品，現在顯示第2頁，所以就查出來第2個商品

GET /ecommerce/_search
{
  "query": {
    "match_all": {}
  },
  "from": 1,
  "size": 1
}

指定查詢出來商品的名稱和價格 類似sql語句的select

GET /ecommerce/_search
{
  "query": {
    "match_all": {}
  },
  "_source": [
    "name",
    "price"
  ]
}

{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 5,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "ecommerce",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "price" : 25,
          "name" : "jiajieshi yagao"
        }
      },
      {
        "_index" : "ecommerce",
        "_type" : "_doc",
        "_id" : "SH1w83ABZ60GR8nZv1rN",
        "_score" : 1.0,
        "_source" : {
          "price" : 40,
          "name" : "zhonghua yagao"
        }
      }
    ]
  }
}

3、query filter

對數據進行過濾

搜索商品名稱包含yagao，而且售價大於等於40元的商品

（gt：大於，lt：小於，gte:大於等於，lte:小於等於）

GET /ecommerce/_search
{
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "name": "yagao"
          }
        }
      ],
      "filter": {
        "range": {
          "price": {
            "gte": 40
          }
        }
      }
    }
  },
  "sort": [
    {
      "price": {
        "order": "desc"
      }
    }
  ]
}

返回的結果

{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 0.03390155,
    "hits" : [
      {
        "_index" : "ecommerce",
        "_type" : "_doc",
        "_id" : "SH1w83ABZ60GR8nZv1rN",
        "_score" : 0.03390155,
        "_source" : {
          "name" : "zhonghua yagao",
          "desc" : "caoben zhiwu",
          "price" : 40,
          "producer" : "zhonghua producer",
          "tags" : [
            "qingxin"
          ]
        }
      }
    ]
  }
}

4、full-text search （全文檢索）

全文檢索會將輸入的搜索串拆解開來，去倒排索引裏面去逐一匹配，只要能匹配上任意一個拆解後的單詞，就可以作爲結果返回。

返回的結果會按照匹配度進行排序

GET /ecommerce/_search
{
 "query": {
   "match": {
     "producer": "yagao producer"
   }
 }
}

返回的結果

{
  "took" : 36,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 1.395052,
    "hits" : [
      {
        "_index" : "ecommerce",
        "_type" : "_doc",
        "_id" : "sBkH-3ABDLwU_RgbxhX0",
        "_score" : 1.395052,
        "_source" : {
          "name" : "special yagao",
          "desc" : "special meibai",
          "price" : 50,
          "producer" : "special yagao producer",
          "tags" : [
            "meibai"
          ]
        }
      }
    ]
  }
}

5、phrase search（短語搜索）

跟全文檢索相對應，要求輸入的搜索串，必須在指定的字段文本中，完全包含一模一樣的，纔可以算匹配，才能作爲結果返回

GET /ecommerce/_search
{
  "query": {
    "match_phrase": {
      "producer": "yagao producer"
    }
  }
}

6、highlight search（高亮搜索結果）

對匹配的producer字段進行高亮顯示

GET /ecommerce/_search
{
  "query": {
    "match": {
      "producer": "yagao"
    }
  },
  "highlight": {
    "fields": {
      "producer": {}
    }
  }
}

返回結果

{
  "took" : 0,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 1.3310189,
    "hits" : [
      {
        "_index" : "ecommerce",
        "_type" : "_doc",
        "_id" : "sBkH-3ABDLwU_RgbxhX0",
        "_score" : 1.3310189,
        "_source" : {
          "name" : "special yagao",
          "desc" : "special meibai",
          "price" : 50,
          "producer" : "special yagao producer",
          "tags" : [
            "meibai"
          ]
        },
        "highlight" : {
          "producer" : [
            "special <em>yagao</em> producer"
          ]
        }
      }
    ]
  }
}

7、term query( 完全匹配 )

term是代表完全匹配，即不進行分詞器分析，文檔中必須包含整個搜索的詞彙

GET /ecommerce/_search
{
  "query": {
    "term": {
      "producer": "special"
    }
  }
}

(terms多值)字段有一多個值時候，用terms關鍵詞查詢，後跟數組

GET /ecommerce/_search
{
  "query": {
    "terms": {
      "producer": [
        "special",
        "producer"
      ]
    }
  }
}