#### 精確值字段(Exact-value Fields) 在結束對于多字段查詢的討論之前的最后一個話題是作為not_analyzed類型的精確值字段。在multi_match查詢中將not_analyzed字段混合到analyzed字段中是沒有益處的。 原因可以通過validate-query進行簡單地驗證，假設我們將title字段設置為not_analyzed： ```Javascript GET /_validate/query?explain { "query": { "multi_match": { "query": "peter smith", "type": "cross_fields", "fields": [ "title", "first_name", "last_name" ] } } } ``` // SENSE: 110_Multi_Field_Search/55_Not_analyzed.json 因為title字段時沒有被解析的，它會以將整個查詢字符串作為一個詞條進行搜索！ title:peter smith ( blended("peter", fields: [first_name, last_name]) blended("smith", fields: [first_name, last_name]) ) 很顯然該詞條在title字段的倒排索引中并不存在，因此永遠不可能被找到。在multi_match查詢中避免使用not_analyzed字段。 <!-- === Exact-Value Fields The final topic that we should touch on before leaving multifield queries is that of exact-value `not_analyzed` fields. ((("not_analyzed fields", "exact value, in multi-field queries")))((("multifield search", "exact value fields")))((("exact values", "exact value not_analyzed fields in multifield search")))((("analyzed fields", "avoiding mixing with not analyzed fields in multi_match queries"))) It is not useful to mix `not_analyzed` fields with `analyzed` fields in `multi_match` queries. The reason for this can be demonstrated easily by looking at a query explanation. Imagine that we have set the `title` field to be `not_analyzed`: [source,js] -------------------------------------------------- GET /_validate/query?explain { "query": { "multi_match": { "query": "peter smith", "type": "cross_fields", "fields": [ "title", "first_name", "last_name" ] } } } -------------------------------------------------- // SENSE: 110_Multi_Field_Search/55_Not_analyzed.json Because the `title` field is not analyzed, it searches that field for a single term consisting of the whole query string! title:peter smith ( blended("peter", fields: [first_name, last_name]) blended("smith", fields: [first_name, last_name]) ) That term clearly does not exist in the inverted index of the `title` field, and can never be found. Avoid using `not_analyzed` fields in `multi_match` queries. -->