Language Analyzers¶

Language-specific analyzers provide a convenient way to create indexes tailored to a particular language. Each language analyzer has built-in stopwords and word divisions based on that language’s usage patterns.

Atlas Search offers analyzers for the following languages:

Arabic	Armenian	Basque	Bengali	Brazilian
Bulgarian	Catalan	CJK	Czech	Danish
Dutch	English	Finnish	French	Galician
German	Greek	Hindi	Hungarian	Indonesian
Irish	Italian	Latvian	Lithuanian	Norwegian
Persian	Portuguese	Romanian	Russian	Sorani
Spanish	Swedish	Turkish	Thai

Example¶

The following example index definition specifies an index on the sujet field using the french analyzer:

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{
  "mappings": {
    "fields": {
      "sujet": {
        "type": "string",
        "analyzer": "lucene.french"
      }
    }
  }
}

Consider a collection named voitures with the following documents:

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{ "_id": 1, "sujet": "Mieux équiper nos voitures pour comprendre les causes d'un accident." }
{ "_id": 2, "sujet": "Le meilleur moment pour le faire c'est immédiatement après que vous aurez fait le plein de carburant." }

The following query uses the index on the sujet field:

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db.voitures.aggregate([
  {
     $searchBeta: {
       "term": {
         "query": "pour",
         "path": "sujet"
        }
     }
  }
])

The above query returns no results when using the french analyzer, because pour is a built-in stop word. Using the standard analyzer, the same query would return both documents.

The following query searches for the string carburant in the sujet field:

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db.voitures.aggregate([
  {
     $searchBeta: {
       "term": {
         "query": "carburant",
         "path": "sujet"
        }
     }
  }
])

The above query returns the document with "_id": 2 from the collection.

{ "_id": 2, "sujet": "Le meilleur moment pour le faire c'est immédiatement après que vous aurez fait le plein de carburant." }

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