Multi Analyzer

Single Field Example

The following example index definition specifies an index on the title field using the standard analyzer. The index definition also specifies lucene.french analyzer as an alternate analyzer for the title field, with the name frenchAnalyzer.

The following query uses the alternate analyzer, named frenchAnalyzer, to search for the string liberte.

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db.movies.aggregate([
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  {
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    "$search": {
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      "text": {
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        "query": "liberte",
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        "path": { "value": "title", "multi": "frenchAnalyzer" }
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      }
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    }
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  },
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  {
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    "$project": {
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      "title": 1,
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      "year": 1,
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      "_id": 0
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    }
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  }
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])

[ { title: 'è Nous la Libertè', year: 1931 } ]

The document in the results is a match because the frenchAnalyzer reduced both the indexed string è Nous la Libertè and query term liberte to the base word libert. Atlas Search won't return this document for a search with the standard analyzer because it doesn't remove diacritics. Each analyzer generates the following tokens (searchable terms) for the index and query:

Multiple Fields Example

The following example index definition specifies an index on the title and plot fields using the standard analyzer. The index definition also specifies lucene.french as an alternate analyzer for the title and the plot fields.

The following query searches for matches for the string revolution in the title and the plot fields by using the alternate analyzer named frenchAnalyzer.

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db.movies.aggregate([
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  {
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    "$search": {
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      "text": {
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        "query": "revolution",
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        "path": ["title", "plot",
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          { "value": "title", "multi": "frenchAnalyzer" },
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          {  "value": "plot", "multi": "frenchAnalyzer" }
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        ]
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      }
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    }
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  },
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  {
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    "$limit": 5
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  },
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  {
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    "$project": {
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      "title": 1,
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      "plot": 1,
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      "year": 1,
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      "_id": 0
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    }
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  }
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])

[
  {
    year: 2012,
    plot: 'REVOLUTION is a film about changing the world, going for it, taking a stand, and fighting for something. A true-life adventure following Director, Rob Stewart (SHARKWATER) over four years ...',
    title: 'Revolution'
  },
  {
    plot: 'New York trapper Tom Dobb becomes an unwilling participant in the American Revolution after his son Ned is drafted into the Army by the villainous Sergeant Major Peasy. Tom attempts to find...',
    title: 'Revolution',
   year: 1985
  },
  {
    plot: "Together with five Soviet avant-garde artists, hero of the Russian revolution Polina Schneider travels to Siberia to 'civilize' the native Khanty and Nenets tribes, for whom interaction ...",
    title: 'Angels of Revolution',
    year: 2014
  },
  {
    plot: 'Two mismatched sets of identical twins - one aristocrat, one peasant - mistakenly exchange identities on the eve of the French Revolution.',
    title: 'Start the Revolution Without Me',
    year: 1970
  },
  {
    plot: "A history of the French Revolution from the decision of the king to convene the Etats-Generaux in 1789 in order to deal with France's debt problem. The first part of the movie tells the ...",
    title: 'La rèvolution franèaise',
    year: 1989
  }
]

The documents in the results contain the query term in both the title and the plot fields. Each analyzer creates the following tokens (searchable terms) for the title field for each document in the results:

For the fifth document in the results, the frenchAnalyzer removed the diacritics in the title field to match the document to the query term.