Scoring¶

Behavior¶

Many factors can influence a document's score, including:

• The position of the search term in the document,
• The frequency of occurrence of the search term in the document,
• The type of operator the query uses,
• The type of analyzer the query uses.

The score assigned to a returned document is part of the document's metadata. You can include each returned document's score along with the result set by using a $project in your aggregation pipeline.

The following example query uses a $project stage to add a field named score to the returned documents:

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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": "Helsinki",
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        "path": "plot"
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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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      plot: 1,
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      title: 1,
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      score: { $meta: "searchScore" }
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    }
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  }
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])

More information about the Lucene scoring algorithm can be found in the Lucene documentation.

Score Modifiers¶

The following score modifying options are available to the search and term operators.

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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": "tower",
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        "path": "title",
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        "score": { "constant": { "value": 5 } }
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      }
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    }
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  },
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  {
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    $project: {
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      "_id": 0,
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      "title": 1,
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      "score": { "$meta": "searchScore" }
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    }
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  }
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])

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{ "title": "Tower Heist", "score": 5 }
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{ "title": "Tokyo Tower", "score": 5 }
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{ "title": "The Leaning Tower", "score": 5 }
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{ "title" : "Tower Block", "score" : 5 }
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{ "title": "Ivory Tower", "score": 5 }