### multi_match查詢 multi_match查詢提供了一個簡便的方法用來對多個字段執行相同的查詢。 > 提示：存在幾種類型的multi_match查詢，其中的3種正好和在["單一查詢字符串"小節中"了解你的數據"單元](../110_Multi_Field_Search/10_Single_query_string.md)中提到的幾種類型相同：best_fields，most_fields以及cross_fields。 默認情況下，該查詢以best_fields類型執行，它會為每個字段生成一個match查詢，然后將這些查詢包含在一個dis_max查詢中。下面的dis_max查詢： ```Javascript { "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 } } ``` 可以通過multi_match簡單地重寫如下： ```Javascript { "multi_match": { "query": "Quick brown fox", "type": "best_fields", <1> "fields": [ "title", "body" ], "tie_breaker": 0.3, "minimum_should_match": "30%" <2> } } ``` // SENSE: 110_Multi_Field_Search/25_Best_fields.json <1> 注意到以上的type屬性為best_fields。 <2> minimum_should_match和operator參數會被傳入到生成的match查詢中。 #### 在字段名中使用通配符 字段名可以通過通配符指定：任何匹配了通配符的字段都會被包含在搜索中。你可以通過下面的查詢來匹配book_title，chapter_title以及section_title字段： ```Javascript { "multi_match": { "query": "Quick brown fox", "fields": "*_title" } } ``` #### 加權個別字段 個別字段可以通過caret語法(^)進行加權：僅需要在字段名后添加^boost，其中的boost是一個浮點數： ```Javascript { "multi_match": { "query": "Quick brown fox", "fields": [ "*_title", "chapter_title^2" ] <1> } } ``` <1> chapter_title字段的boost值為2，而book_title和section_title字段的boost值為默認的1。 <!-- [[multi-match-query]] === multi_match Query The `multi_match` query provides ((("multifield search", "multi_match query")))((("multi_match queries")))((("match query", "multi_match queries"))) a convenient shorthand way of running the same query against multiple fields. [NOTE] ==== There are several types of `multi_match` query, three of which just happen to coincide with the three scenarios that we listed in <<know-your-data>>: `best_fields`, `most_fields`, and `cross_fields`. ==== By default, this query runs as type `best_fields`, which means((("best fields queries", "multi-match queries")))((("dis_max (disjunction max) query", "multi_match query wrapped in"))) that it generates a `match` query for each field and wraps them in a `dis_max` query. This `dis_max` query [source,js] -------------------------------------------------- { "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 } } -------------------------------------------------- could be rewritten more concisely with `multi_match` as follows: [source,js] -------------------------------------------------- { "multi_match": { "query": "Quick brown fox", "type": "best_fields", <1> "fields": [ "title", "body" ], "tie_breaker": 0.3, "minimum_should_match": "30%" <2> } } -------------------------------------------------- // SENSE: 110_Multi_Field_Search/25_Best_fields.json <1> The `best_fields` type is the default and can be left out. <2> Parameters like `minimum_should_match` or `operator` are passed through to the generated `match` queries. ==== Using Wildcards in Field Names Field names can be specified with wildcards: any field that matches the wildcard pattern((("multi_match queries", "wildcards in field names")))((("wildcards in field names")))((("fields", "wildcards in field names"))) will be included in the search. You could match on the `book_title`, `chapter_title`, and `section_title` fields, with the following: [source,js] -------------------------------------------------- { "multi_match": { "query": "Quick brown fox", "fields": "*_title" } } -------------------------------------------------- ==== Boosting Individual Fields Individual fields can be boosted by using the caret (`^`) syntax: just add `^boost` after the field((("multi_match queries", "boosting individual fields")))((("boost parameter", "boosting individual fields in multi_match queries"))) name, where `boost` is a floating-point number: [source,js] -------------------------------------------------- { "multi_match": { "query": "Quick brown fox", "fields": [ "*_title", "chapter_title^2" ] <1> } } -------------------------------------------------- <1> The `chapter_title` field has a `boost` of `2`, while the `book_title` and `section_title` fields have a default boost of `1`. -->