Elasticsearch 多字段搜索

1，最佳字段

• dis_max 查詢（分離最大化查詢，Disjunction Max Query):將任何與任一查詢匹配的文檔作為結果返回，但只將最佳匹配的評分作為查詢的評分結果返回；

// 1，初始化數據
PUT /my_index/my_type/1
{
    "title": "Quick brown rabbits",
    "body":  "Brown rabbits are commonly seen."
}

PUT /my_index/my_type/2
{
    "title": "Keeping pets healthy",
    "body":  "My quick brown fox eats rabbits on a regular basis."
}


// 2，dis_max 查詢
GET /my_index/my_type/_search
{
    "query": {
        "dis_max": {
            "queries": [
                { "match": { "title": "Brown fox" }},
                { "match": { "body":  "Brown fox" }}
            ]
        }
    }
}

2，multi_match查詢

• multi_match查詢為能在多個字段上反復執行相同查詢提供了一種便捷方式；

// 初始版本
{
  "dis_max": {
    "queries":  [
      {
        "match": {
          "title": {
            "query": "Quick brown fox",
            "minimum_should_match": "30%"
          }
        }
      },
      {
        "match": {
          "body": {
            "query": "Quick brown fox",
            "minimum_should_match": "30%"
          }
        }
      },
    ],
    "tie_breaker": 0.3
  }
}


// multi_match 簡潔形式
{
  "multi_match":{
    "query":"Quick brown fox",
    "type":"best_fields",
    "fields":["title","body"],
    "tie_breaker":0.3,
    "minimum_should_match":"30%"
  }
}

3，多數字段

// 1，多字段映射
DELETE /my_index

PUT /my_index
{
    "settings": { "number_of_shards": 1 }, 
    "mappings": {
        "my_type": {
            "properties": {
                "title": { 
                    "type":     "text",
                    "analyzer": "english",
                    "fields": {
                        "std":   { 
                            "type":     "text",
                            "analyzer": "standard"
                        }
                    }
                }
            }
        }
    }
}


// 2, 初始化數據
PUT /my_index/my_type/1
{ "title": "My rabbit jumps" }

PUT /my_index/my_type/2
{ "title": "Jumping jack rabbits" }


// 3，簡單搜索
GET /my_index/_search
{
   "query": {
        "match": {
            "title": "jumping rabbits"
        }
    }
}


// 3.1 multi_match 搜索
GET /my_index/_search
{
   "query": {
        "multi_match": {
            "query":  "jumping rabbits",
            "type":   "most_fields", 
            "fields": [ "title", "title.std" ]
        }
    }
}


// 3.2 通過boost自定義最終評分貢獻
GET /my_index/_search
{
   "query": {
        "multi_match": {
            "query":       "jumping rabbits",
            "type":        "most_fields",
            "fields":      [ "title^10", "title.std" ] 
        }
    }
}

4，cross-fields跨字段查詢

// 字段中心式的 most_fields 查詢的 explanation
GET /_validate/query?explain
{
  "query":{
    "multi_match": {
      "query": "peter smith",
      "type": "most_fields",
      "operator": "and",
      "fields":["first_name", "last_name"]
    }
  }
}


// 詞中心式的 cross_fields 查詢的 explanation
GET /_validate/query?explain
{
  "query":{
    "multi_match": {
      "query": "peter smith",
      "type": "cross_fields",
      "operator": "and",
      "fields":["first_name", "last_name"]
    }
  }
}

**參考資料：** -[多字段搜索](https://www.elastic.co/guide/cn/elasticsearch/guide/current/multi-field-search.html)