This information applies to version 2.x of Elasticsearch. For the
most up to date information, see the current version of the
Elasticsearch Reference.
In That Caseedit
The most frequently used token filter is the lowercase
filter, which does
exactly what you would expect; it transforms
each token into its lowercase
form:
It doesn’t matter whether users search for fox
or FOX
, as long as the same
analysis process is applied at query time and at search time. The lowercase
filter will transform a query for FOX
into a query for fox
, which is the
same token that we have stored in our inverted index.
To use token filters as part of the analysis process, we
can create a custom
analyzer:
PUT /my_index { "settings": { "analysis": { "analyzer": { "my_lowercaser": { "tokenizer": "standard", "filter": [ "lowercase" ] } } } } }
And we can test it out with the analyze
API: