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Multi Analyzer

You can use the multi object in your index definition to specify alternate analyzers with which to also index the field. When you index a field with alternate analyzers in addition to the default analyzer, you can search the collection with either the default or the alternate analyzer. This page demonstrates how to specify alternate analyzers in your index definition using multi. To learn more about searching with alternate analyzers, see Construct a Query Path.

Note

The multi path option is available only to fields of type string.

The following example index definition specifies an index on the title field in the sample_mflix.movies collection using the standard analyzer. The index definition also specifies keyword analyzer as an alternate analyzer for the title field, with the name keywordAnalyzer. The Keyword Analyzer analyzer indexes the entire field as a single term, so it returns results only if the search term and the specified field match exactly.

{
"mappings": {
"dynamic": false,
"fields": {
"title": {
"type": "string",
"analyzer": "lucene.standard",
"multi": {
"keywordAnalyzer": {
"type": "string",
"analyzer": "lucene.keyword"
}
}
}
}
}
}

The following query uses the alternate analyzer, named keywordAnalyzer, to search for exact matches on the string The Count of Monte Cristo.

db.movies.aggregate([
{
$search: {
"text": {
"query": "The Count of Monte Cristo",
"path": { "value": "title", "multi": "keywordAnalyzer" }
}
}
},
{
$project: {
"title": 1,
"year": 1,
"_id": 0
}
}
])

The above query returns the following results:

{ "title" : "The Count of Monte Cristo", "year" : 1934 }
{ "title" : "The Count of Monte Cristo", "year" : 1954 }
{ "title" : "The Count of Monte Cristo", "year" : 1998 }

By contrast, the same query using the standard analyzer would find all the movies with the word Count or Monte or Cristo in the title.

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