Return Atlas Search Results or Metadata

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$search

Definition
Fields
Behavior
Aggregation Variable
$searchMeta
Definition
Fields
Behavior
Metadata Result Types
Example
Troubleshooting

Atlas Search queries take the form of an aggregation pipeline stage. Based on the pipeline stage that you choose, your query returns either the search results of a full-text search or metadata about your search results:

Aggregation Pipeline Stage	Purpose
`$search`	Return the search results of a full-text search.
`$searchMeta`	Return metadata about your search results.

`$search`

Definition

The $search stage performs a full-text search on the specified field or fields which must be covered by an Atlas Search index.

$search

A $search pipeline stage has the following prototype form:

{
  $search: {
    "index": "<index-name>",
    "<operator-name>"|"<collector-name>": {
      <operator-specification>|<collector-specification>
    },
    "highlight": {
      <highlight-options>
    },
    "count": {
      <count-options>
    },
    "scoreDetails": true| false,
    "returnStoredSource": true | false
  }
}

Fields

The $search stage takes a document with the following fields:

Field	Type	Necessity	Description
`<collector-name>`	document	Conditional	Name of the collector to use with the query. You can provide a document that contains the collector-specific options as the value for this field. Either this or `<operator-name>` is required.
`count`	document	Optional	Document that specifies the count options for retrieving a count of the results. To learn more, see Count Atlas Search Results.
`highlight`	document	Optional	Document that specifies the highlight options for displaying search terms in their original context.
`index`	string	Optional	Name of the Atlas Search index to use. If omitted, defaults to `default`. Note If you name your index `default`, you don't need to specify an `index` parameter when using the $search pipeline stage. Otherwise, you must specify the index name using the `index` parameter. Atlas Search doesn't returns results if you misspell the index name or if the specified index doesn't already exist on the cluster.
`<operator-name>`	document	Conditional	Name of the operator to search with. You can provide a document that contains the operator-specific options as the value for this field. Either this or `<collector-name>` is required. Use the compound operator to run a compound query with multiple operators.
`returnStoredSource`	boolean	Optional	Flag that specifies whether to perform a full document lookup on the backend database or return only stored source fields directly from Atlas Search. If omitted, defaults to `false`. To learn more, see Return Stored Source Fields.
`scoreDetails`	boolean	Optional	Flag that specifies whether to retrieve a detailed breakdown of the score for the documents in the results. If omitted, defaults to `false`. To view the details, you must use the $meta expression in the `$project` stage. To learn more, see Return the Score Details.

Behavior

$search must be the first stage of any pipeline it appears in. $search cannot be used in:

a view definition
a $facet pipeline stage

Aggregation Variable

$search returns only the results of your query. The metadata results of your $search query are saved in the $$SEARCH_META aggregation variable. You can use the $$SEARCH_META variable to view the metadata results for your $search query. The $$SEARCH_META aggregation variable can be used anywhere after a $search stage in any pipeline, but it can't be used after the $lookup or $unionWith stage in any pipeline. The $$SEARCH_META aggregation variable can't be used in any subsequent stage after a $searchMeta stage.

Example

Suppose the following index on the sample_mflix.movies collection.

{
  "mappings": {
    "dynamic": false,
    "fields": {
      "released": {
        "type": "date"
      }
    }
  }
}

The following query searches for movies released near September 01, 2011 using the $search stage. The query includes a:

$project stage to exclude all fields in the documents except title and released.
$facet stage that outputs a:
- docs field with an array of the top 5 search results
- meta field with the value of $$SEARCH_META variable

db.movies.aggregate([
  {
    "$search": {
      "near": {
        "path": "released",
        "origin": ISODate("2011-09-01T00:00:00.000+00:00"),
        "pivot": 7776000000
      }
    }
  },
  {
    $project: {
      "_id": 0,
      "title": 1,
      "released": 1
    }
  },
  { "$limit": 5 },
  {
    "$facet": {
      "docs": [],
      "meta": [
        {"$replaceWith": "$$SEARCH_META"},
        {"$limit": 1}
      ]
    }
  }
])

{
  "docs" : [
    {
      "title" : "Submarino",
      "released" : ISODate("2011-09-01T00:00:00Z")
    },
    {
      "title" : "Devil's Playground",
      "released" : ISODate("2011-09-01T00:00:00Z")
    },
    {
      "title" : "Bag It",
      "released" : ISODate("2011-09-01T00:00:00Z")
    },
    {
      "title" : "Dos",
      "released" : ISODate("2011-09-01T00:00:00Z")
    },
    {
      "title" : "We Were Here",
      "released" : ISODate("2011-09-01T00:00:00Z")
    }
  ],
  "meta" : [
    { "count" : { "lowerBound" : NumberLong(17373) } }
  ]
}

To learn more about the $$SEARCH_META variable and its usage, see:

`$searchMeta`

Note

To run $searchMeta queries over sharded collections, your cluster must run MongoDB v6.0 or later.

Definition

The $searchMeta stage returns different types of metadata result documents.

$searchMeta

A $searchMeta pipeline stage has the following prototype form:

{
  $searchMeta: {
    "index": "<index-name>",
    "<collector-name>"|"<operator-name>": {
      <collector-specification>|<operator-specification>
    },
    "count": {
      <count-options>
    }
  }
}

Fields

The $searchMeta stage takes a document with the following fields:

Field	Type	Necessity	Description
`<collector-name>`	document	Conditional	Name of the collector to use with the query. You can provide a document that contains the collector-specific options as the value for this field. Value must be `facet` to retrieve a mapping of the defined facet names to an array of buckets for that facet. To learn more, see facet. You must specify this or `<operator-name>`.
`count`	document	Optional	Document that specifies the count options for retrieving a count of the results. To learn more, see Count Atlas Search Results.
`index`	string	Optional	Name of the Atlas Search index to use. If omitted, defaults to `default`. Atlas Search doesn't return results if you misspell the index name or if the specified index doesn't already exist on the cluster.
`<operator-name>`	document	Conditional	Name of the operator to search with. You can provide a document that contains the operator-specific options as the value for this field. You must specify this or `<collector-name>`. `$searchMeta` returns the default `count` metadata only.

Behavior

The $searchMeta stage must be the first stage in any pipeline.

Metadata Result Types

The structure of the metadata results document that is returned by the $searchMeta stage varies based on the type of results. Atlas Search supports the following result types:

Type	Result Structure
`count`	The count result included in the results indicate whether the count returned in the results is a total count of the search results, or a lower bound. To learn more, see Count Results.
`facet`	The result to a facet query is a mapping of the defined facet names to an array of buckets for that facet. To learn more, see Facet Results.

Example

Suppose the following index on the sample_mflix.movies collection.

{
  "mappings": {
    "dynamic": false,
    "fields": {
      "year": {
        "type": "number"
      }
    }
  }
}

The following query searches for the number of movies released in 1998 using the $searchMeta stage.

db.movies.aggregate([
  {
    "$searchMeta": {
      "range": {
        "path": "year",
        "gte": 1998,
        "lt": 1999
      },
      "count": {
        "type": "total"
      }
    }
  }
])

[ { count: { total: Long("552") } } ]

Troubleshooting

If you are experiencing issues with your Atlas Search $search queries, see Troubleshoot Atlas Search Errors.

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