# normalizer(归一化) 原文链接 : [https://www.elastic.co/guide/en/elasticsearch/reference/current/normalizer.html](https://www.elastic.co/guide/en/elasticsearch/reference/current/normalizer.html) 译文链接 : [normalizer(归一化)](/pages/viewpage.action?pageId=9406034) 贡献者 : [程威](/display/~chengwei)，[ApacheCN](/display/~apachecn)，[Apache中文网](/display/~apachechina) **[`keyword`](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/keyword.html "Keyword datatype")**** fields**（关键字字段） 的 **`normalizer`**`（`归一化）属性与 [`analyzer`](https://www.elastic.co/guide/en/elasticsearch/reference/5.3/analyzer.html "analyzer")`（`分析器）类似,只不过它保证 **analysis chain**（分析链）生成单一的 **`token` **`（词元`）. **`normalizer`**`（`归一化）应用于索引 **keyword**（关键字）之前,以及诸如在 **`[match](https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-match-query.html) query `**(匹配查询),查询解析器搜索 **keyword**** fields**（关键字字段）的时候. ``` curl -XPUT 'localhost:9200/index?pretty' -H 'Content-Type: application/json' -d' { "settings": { "analysis": { "normalizer": { "my_normalizer": { "type": "custom", "char_filter": [], "filter": ["lowercase", "asciifolding"] } } } }, "mappings": { "type": { "properties": { "foo": { "type": "keyword", "normalizer": "my_normalizer" } } } } } ' curl -XPUT 'localhost:9200/index/type/1?pretty' -H 'Content-Type: application/json' -d' { "foo": "BÀR" } ' curl -XPUT 'localhost:9200/index/type/2?pretty' -H 'Content-Type: application/json' -d' { "foo": "bar" } ' curl -XPUT 'localhost:9200/index/type/3?pretty' -H 'Content-Type: application/json' -d' { "foo": "baz" } ' curl -XPOST 'localhost:9200/index/_refresh?pretty' curl -XGET 'localhost:9200/index/_search?pretty' -H 'Content-Type: application/json' -d' { "query": { "match": { "foo": "BAR" } } } ' ``` 上述查询与 **documents（文档） 1** 和 **2** 相匹配,这是因为在索引和查询的时候都将 **`BAR `**转换为了 **`bar`**. ``` { "took": $body.took, "timed_out": false, "_shards": { "total": 5, "successful": 5, "failed": 0 }, "hits": { "total": 2, "max_score": 0.2876821, "hits": [ { "_index": "index", "_type": "type", "_id": "2", "_score": 0.2876821, "_source": { "foo": "bar" } }, { "_index": "index", "_type": "type", "_id": "1", "_score": 0.2876821, "_source": { "foo": "BÀR" } } ] } } ``` 此外,**keywords **在索引之前转换意味着聚合返回 **normalised values**（归一化的值）: ``` curl -XGET 'localhost:9200/index/_search?pretty' -H 'Content-Type: application/json' -d' { "size": 0, "aggs": { "foo_terms": { "terms": { "field": "foo" } } } } ' ``` 返回 ``` { "took": 43, "timed_out": false, "_shards": { "total": 5, "successful": 5, "failed": 0 }, "hits": { "total": 3, "max_score": 0.0, "hits": [] }, "aggregations": { "foo_terms": { "doc_count_error_upper_bound": 0, "sum_other_doc_count": 0, "buckets": [ { "key": "bar", "doc_count": 2 }, { "key": "baz", "doc_count": 1 } ] } } } ```