#### 精确值字段(Exact-value Fields) 在结束对于多字段查询的讨论之前的最后一个话题是作为not_analyzed类型的精确值字段。在multi_match查询中将not_analyzed字段混合到analyzed字段中是没有益处的。 原因可以通过validate-query进行简单地验证，假设我们将title字段设置为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 因为title字段时没有被解析的，它会以将整个查询字符串作为一个词条进行搜索！ title:peter smith ( blended("peter", fields: [first_name, last_name]) blended("smith", fields: [first_name, last_name]) ) 很显然该词条在title字段的倒排索引中并不存在，因此永远不可能被找到。在multi_match查询中避免使用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. -->