Index Reference

An MongoDB Search index is a data structure that maps documents from your Atlas cluster to the terms that are extracted from those documents. MongoDB Search indexes enable efficient full-text searches of your database.

When you define an MongoDB Search index, you can use static or dynamic mappings to specify which fields you want to index in your collection. You can also use analyzers to define how MongoDB Search extracts searchable tokens from string fields or query strings. Finally, you can apply additional configuration options in your index definition to improve the performance and accuracy of your MongoDB Search query, including options to store source fields in your index, or define synonym mappings.

To learn how to define an MongoDB Search index according to your your query requirements, see Manage MongoDB Search Indexes. Once you define your MongoDB Search index, you can add the index to your Atlas cluster with the Create an MongoDB Search Index tutorial. To learn how to view, edit, update, or delete your MongoDB Search index, see Supported Clients.

This page describes the JSON syntax and definition options for an MongoDB Search index.

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": <integer>,
9   "analyzers": [ <custom-analyzer> ],
10   "storedSource": <boolean> | {
11     <stored-source-definition>
12   },
13   "synonyms": [
14     {
15       <synonym-mapping-definition>
16     }
17   ] 
18 }
19

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, MongoDB 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`, MongoDB 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: MongoDB Search dynamically indexes all fields in a `document` using the default settings for the detected data type. MongoDB 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`. If omitted, defaults to `1`. To use index partitions, you must have search nodes deployed in your cluster.
`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 MongoDB 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 7.0+ If omitted, defaults to `false`. To learn more, see Define Stored Source Fields in Your MongoDB 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 MongoDB Search Index.

Troubleshoot Indexes

`mongot` Process Not Installed or Running

The following error is returned if you run $search queries when the MongoDB 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 MongoDB Search index is defined. If you don't have any MongoDB Search index in your Atlas cluster, create at least one MongoDB Search index to resolve this error.

Learn More

To learn how to define an MongoDB Search index to meet your MongoDB Search query needs, see Manage MongoDB Search Indexes.

To learn how to add an index to your Atlas cluster, see Create an MongoDB Search Index.

To learn more about the available index configuration options, see the following reference pages:

Back

Manage Indexes

Analyzers

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": <integer>,
9	"analyzers": [ <custom-analyzer> ],
10	"storedSource": <boolean> \| {
11	<stored-source-definition>
12	},
13	"synonyms": [
14	{
15	<synonym-mapping-definition>
16	}
17	]
18	}
19

Syntax

Options

Troubleshoot Indexes

mongot Process Not Installed or Running

Learn More

`mongot` Process Not Installed or Running