IMPORTANT: No additional bug fixes or documentation updates
will be released for this version. For the latest information, see the
current release documentation.
similarity
editsimilarity
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:
-
BM25 - The Okapi BM25 algorithm. The algorithm used by default in Elasticsearch and Lucene.
-
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:
resp = client.indices.create(
index="my-index-000001",
mappings={
"properties": {
"default_field": {
"type": "text"
},
"boolean_sim_field": {
"type": "text",
"similarity": "boolean"
}
}
},
)
print(resp)
response = client.indices.create(
index: 'my-index-000001',
body: {
mappings: {
properties: {
default_field: {
type: 'text'
},
boolean_sim_field: {
type: 'text',
similarity: 'boolean'
}
}
}
}
)
puts response
const response = await client.indices.create({
index: "my-index-000001",
mappings: {
properties: {
default_field: {
type: "text",
},
boolean_sim_field: {
type: "text",
similarity: "boolean",
},
},
},
});
console.log(response);