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