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normalizer
editnormalizer
editThe normalizer
property of keyword
fields is similar to
analyzer
except that it guarantees that the analysis chain
produces a single token.
The normalizer
is applied prior to indexing the keyword, as well as at
search-time when the keyword
field is searched via a query parser such as
the match
query.
PUT index { "settings": { "analysis": { "normalizer": { "my_normalizer": { "type": "custom", "char_filter": [], "filter": ["lowercase", "asciifolding"] } } } }, "mappings": { "type": { "properties": { "foo": { "type": "keyword", "normalizer": "my_normalizer" } } } } } PUT index/type/1 { "foo": "BÀR" } PUT index/type/2 { "foo": "bar" } PUT index/type/3 { "foo": "baz" } POST index/_refresh GET index/_search { "query": { "match": { "foo": "BAR" } } }
The above query matches documents 1 and 2 since BÀR
is converted to bar
at
both index and query time.
{ "took": $body.took, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped" : 0, "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" } } ] } }
Also, the fact that keywords are converted prior to indexing also means that aggregations return normalized values:
GET index/_search { "size": 0, "aggs": { "foo_terms": { "terms": { "field": "foo" } } } }
returns
{ "took": 43, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped" : 0, "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 } ] } } }