Hunspell Token Filteredit

Basic support for hunspell stemming. Hunspell dictionaries will be picked up from a dedicated hunspell directory on the filesystem (<path.conf>/hunspell). Each dictionary is expected to have its own directory named after its associated locale (language). This dictionary directory is expected to hold a single *.aff and one or more *.dic files (all of which will automatically be picked up). For example, assuming the default hunspell location is used, the following directory layout will define the en_US dictionary:

- conf
    |-- hunspell
    |    |-- en_US
    |    |    |-- en_US.dic
    |    |    |-- en_US.aff

Each dictionary can be configured with one setting:

ignore_case
If true, dictionary matching will be case insensitive (defaults to false)

This setting can be configured globally in elasticsearch.yml using

  • indices.analysis.hunspell.dictionary.ignore_case

or for specific dictionaries:

  • indices.analysis.hunspell.dictionary.en_US.ignore_case.

It is also possible to add settings.yml file under the dictionary directory which holds these settings (this will override any other settings defined in the elasticsearch.yml).

One can use the hunspell stem filter by configuring it the analysis settings:

{
    "analysis" : {
        "analyzer" : {
            "en" : {
                "tokenizer" : "standard",
                "filter" : [ "lowercase", "en_US" ]
            }
        },
        "filter" : {
            "en_US" : {
                "type" : "hunspell",
                "locale" : "en_US",
                "dedup" : true
            }
        }
    }
}

The hunspell token filter accepts four options:

locale
A locale for this filter. If this is unset, the lang or language are used instead - so one of these has to be set.
dictionary
The name of a dictionary. The path to your hunspell dictionaries should be configured via indices.analysis.hunspell.dictionary.location before.
dedup
If only unique terms should be returned, this needs to be set to true. Defaults to true.
longest_only
If only the longest term should be returned, set this to true. Defaults to false: all possible stems are returned.
Note

As opposed to the snowball stemmers (which are algorithm based) this is a dictionary lookup based stemmer and therefore the quality of the stemming is determined by the quality of the dictionary.

Dictionary loadingedit

By default, the default Hunspell directory (config/hunspell/) is checked for dictionaries when the node starts up, and any dictionaries are automatically loaded.

Dictionary loading can be deferred until they are actually used by setting indices.analysis.hunspell.dictionary.lazy to `true`in the config file.

Referencesedit

Hunspell is a spell checker and morphological analyzer designed for languages with rich morphology and complex word compounding and character encoding.