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The Atlas Search Aggregation Pipeline Stages

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  • $search
  • Aggregation Variable
  • $searchMeta
  • Troubleshoot Errors
Important

Looking for $searchBeta? Use $search instead, the official aggregation stage for running search queries.

Atlas Search queries take the form of an aggregation pipeline stage. This page describes the following pipeline stages:

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

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

A $search pipeline stage has the following prototype form:

{
$search: {
"index": "<index-name>",
"<operator-name>"|"<collector-name>": {
<specification(s)>
},
"highlight": {
<highlight-options>
}
}
}

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.
highlight
document
Optional
Document that specifies the Highlighting 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.
<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.

$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 in all supported aggregation pipeline stages to view the metadata results for your $search query.

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

The query returns the following results:

{
"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:

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

$searchMeta

A $searchMeta pipeline stage has the following prototype form:

{
$searchMeta: {
"index": "<index-name>",
"<result-type>": {
<result-type-specification>
}
}
}

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

Field
Type
Necessity
Description
index
string
Optional
Name of the Atlas Search index to use. If omitted, defaults to default.
<result-type>
document
Required

Type of result to return. You can provide a document as the value for this field. Value can be one of the following:

  • count - for a count of the results. To learh more, see Counting.
  • facet - for a mapping of the defined facet names to an array of buckets for that facet. To learn more, see facet.

To learn more, see 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.

The following error is returned if you run $search queries when the Atlas Search mongot process isn't installed or running:

MongoError: Remote error from mongot :: caused by :: Error connecting to localhost:28000.

The mongot process is installed only when the first Atlas Search index is defined. If you don't have any Atlas Search index in your Atlas cluster, create at least one Atlas Search index to resolve this error.

Tip
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