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Normalizers
editNormalizers
editThis functionality is in beta and is subject to change. The design and code is less mature than official GA features and is being provided as-is with no warranties. Beta features are not subject to the support SLA of official GA features.
Normalizers are similar to analyzers except that they may only emit a single token. As a consequence, they do not have a tokenizer and only accept a subset of the available char filters and token filters. Only the filters that work on a per-character basis are allowed. For instance a lowercasing filter would be allowed, but not a stemming filter, which needs to look at the keyword as a whole.
Custom normalizers
editElasticsearch does not ship with built-in normalizers so far, so the only way to get one is by building a custom one. Custom normalizers take a list of char character filters and a list of token filters.
PUT index
{
"settings": {
"analysis": {
"char_filter": {
"quote": {
"type": "mapping",
"mappings": [
"« => \"",
"» => \""
]
}
},
"normalizer": {
"my_normalizer": {
"type": "custom",
"char_filter": ["quote"],
"filter": ["lowercase", "asciifolding"]
}
}
}
},
"mappings": {
"type": {
"properties": {
"foo": {
"type": "keyword",
"normalizer": "my_normalizer"
}
}
}
}
}