Review Atlas Search Index Syntax

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Syntax

Options

Atlas Search can index data in different ways. When you define an Atlas Search index, you can specify a particular analyzer or multiple analyzers to index certain fields. To learn more, see Process Data with Analyzers. You can also index certain fields and omit others, or you can dynamically index all the fields in a collection. To learn more, see Define Field Mappings. You can define Atlas Search indexes through the Atlas UI, Atlas Search API, Atlas CLI, mongosh, or Drivers.

This page describes the JSON syntax and fields for an Atlas Search index.

Important

If you use the $out aggregation stage to modify a collection with an Atlas Search index, you must delete and re-create the search index. If possible, consider using $merge instead of $out.

Syntax

1 { 
2   "mappings": { 
3     "dynamic": <boolean>, 
4     "fields": { <field-definition> } 
5   }
6 }
7

1 {  
2   "analyzer": "<analyzer-for-index>", 
3   "searchAnalyzer": "<analyzer-for-query>", 
4   "mappings": { 
5     "dynamic": <boolean>, 
6     "fields": { <field-definition> } 
7   },
8   "numPartitions": 4,
9   "analyzers": [ <custom-analyzer> ],
10   "storedSource": <boolean> | {
11     <stored-source-definition>
12   },
13   "synonyms": [
14     {
15       "name": "<synonym-mapping-name>",
16       "source": {
17         "collection": "<source-collection-name>"
18       },
19       "analyzer": "<synonym-mapping-analyzer>"
20     }
21   ] 
22 }
23

Options

Field	Type	Necessity	Description
`analyzer`	string	Optional	Specifies the analyzer to apply to string fields when indexing. If you set this only at the top and do not specify an analyzer for the fields in the index definition, Atlas Search applies this analyzer to all the fields. To use a different analyzer for each field, you must specify a different analyzer for the field. If omitted, defaults to Standard Analyzer.
`analyzers`	array of Custom Analyzers	Optional	Specifies the Custom Analyzers to use in this index.
`mappings`	Document Field Definition	Required	Specifies how to index fields at different paths for this index.
`mappings.dynamic`	boolean	Optional	Enables or disables dynamic mapping of fields for this index. If set to `true`, Atlas Search recursively indexes all dynamically indexable fields. If set to `false`, you must specify individual fields to index using `mappings.fields`. If omitted, defaults to `false`. IMPORTANT: Atlas Search dynamically indexes all fields in a `document` using the default settings for the detected data type. Atlas Search also dynamically indexes all nested documents under the `document`, unless you explicitly override by setting `dynamic` to `false`. For example index configurations, see Static Mapping Example or Combined Mapping Example
`mappings.fields`	document	Conditional	Specifies the fields that you would like to index. Required only if dynamic mapping is disabled. You can't index fields that contain the dollar (`$`) sign at the start of the field name. To learn more, see Define Field Mappings.
`searchAnalyzer`	string	Optional	Specifies the analyzer to apply to query text before searching with it. If omitted, defaults to the analyzer that you specify for the `analyzer` option. If you omit both the `searchAnalyzer` and the `analyzer` options, defaults to the Standard Analyzer.
`numPartitions`	int	Optional	Specifies the number of sub-indexes to create if the document count exceeds two billion. The following values are valid: `1`, `2`, `4`, `8`, `16`, `32`, `64`. If omitted, defaults to `1`. To use index partitions, you must have search nodes deployed in your cluster. Important The `numPartitions` option is available as a Preview feature.
`storedSource`	boolean or Stored Source Definition	Optional	Specifies fields in the documents to store for query-time look-ups using the returnedStoredSource option. You can store fields of all Data Types on Atlas Search. Value can be one of the following: `true`, to store all fields `false`, to not store any fields Object that specifies the fields to `include` or `exclude` from storage `storedSource` is only available on Atlas clusters running one of the following versions: MongoDB 5.0.6+ MongoDB 6.0+ MongoDB 7.0+ If omitted, defaults to `false`. To learn more, see Define Stored Source Fields in Your Atlas Search Index.
`synonyms`	array of Synonym Mapping Definition	Optional	Synonym mappings to use in your index. An index definition can have only one synonym mapping. To learn more, see Define Synonym Mappings in Your Atlas Search Index.

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4: Configure Synonym Mappings

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1	{
2	"mappings": {
3	"dynamic": <boolean>,
4	"fields": { <field-definition> }
5	}
6	}
7

1	{
2	"analyzer": "<analyzer-for-index>",
3	"searchAnalyzer": "<analyzer-for-query>",
4	"mappings": {
5	"dynamic": <boolean>,
6	"fields": { <field-definition> }
7	},
8	"numPartitions": 4,
9	"analyzers": [ <custom-analyzer> ],
10	"storedSource": <boolean> \| {
11	<stored-source-definition>
12	},
13	"synonyms": [
14	{
15	"name": "<synonym-mapping-name>",
16	"source": {
17	"collection": "<source-collection-name>"
18	},
19	"analyzer": "<synonym-mapping-analyzer>"
20	}
21	]
22	}
23