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similarity
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similarity
editElasticsearch allows you to configure a text scoring algorithm or similarity per field. The similarity setting provides a simple way of choosing a text similarity algorithm other than the default BM25, such as boolean.
Only text-based field types like text and keyword support this configuration.
Custom similarities can be configured by tuning the parameters of the built-in similarities. For more details about this expert options, see the similarity module.
The only similarities which can be used out of the box, without any further configuration are:
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BM25 - The Okapi BM25 algorithm. The algorithm used by default in Elasticsearch and Lucene.
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boolean - A simple boolean similarity, which is used when full-text ranking is not needed and the score should only be based on whether the query terms match or not. Boolean similarity gives terms a score equal to their query boost.
The similarity can be set on the field level when a field is first created, as follows:
response = client.indices.create( index: 'my-index-000001', body: { mappings: { properties: { default_field: { type: 'text' }, boolean_sim_field: { type: 'text', similarity: 'boolean' } } } } ) puts response