Manage Indexes

The new Data Explorer user interface is available in Public Preview and includes new features that weren't present in the old interface.

Indexes are special data structures that improve query performance. Indexes store a portion of a collection's data in an easy-to-traverse form. The index stores the value of a specific field or set of fields, ordered by the value of the field.

To improve query performance, build indexes on fields that appear often in queries and for all operations that sort by a field.

Queries on an indexed field can use the index to limit the number of documents that must be scanned to find matching documents.
Sort operations on an indexed field can return documents pre-sorted by the index.

To learn more about indexes, see Indexes.

Note

Considerations

Indexes have some negative performance impact on write operations. For collections with high write-to-read ratio, indexes are expensive since each insert must also update any indexes. For a detailed list of considerations for indexes, see Operational Considerations for Indexes.

Required Roles

To create, drop, or hide indexes, you must have access provided by at least one of the following roles:

Considerations

By default, you can have up to three concurrent index builds. To learn more, see Maximum Concurrent Index Builds.

Indexes Tab

The Indexes tab lists the existing indexes for a collection.

To access the Indexes tab for a collection, click on the collection on the left hand pane and select the Indexes tab.

click to enlarge

For each index, Atlas displays the following information:

Name and Definition	The name of the index and keys.
Type	Regular, text, geospatial or hashed index.
Size	How large the index is.
Usage	Number of times the index has been used in a lookup since the time the index was created or the last server restart.
Properties	Any special properties (such as uniqueness, partial) of the index.

Create an Index

Open the index creation dialog

From the Indexes tab, click the Create Index button.

Add fields to the index

Specify an index key.
- To specify an existing document field as an index key, select the field from the dropdown list.
- To specify a field that does not exist in any document as an index key, enter the field name in the input box.
- To create a compound index, click the icon next to the index type dropdown.
Use the dropdown to the right of each field name to specify the index type. You can specify one of the following types:
- Ascending
- Descending
- 2dsphere
- Text

Optional. Specify index options

Atlas supports the following index options:

Option

Description

More Information

Create unique index

Ensure that the indexed fields do not store duplicate values.

You cannot perform a rolling build for a unique index. If you enable building indexes in a rolling fashion with the unique index option, Atlas rejects your configuration with an error message.

Unique Indexes

Index name

Specify a name for the index.

Specify an Index Name

Create a TTL index

Delete documents automatically after a specified number of seconds since the indexed field value.

TTL Indexes

Partial filter expression

Index only the documents which match the specified filter expression.

For example:

The following partial filter expression only indexes documents where the timezone field exists:

{ "timezone": { "$exists": true } }

Partial Indexes

Wildcard projection

Support unknown or arbitrary fields which match the specified projection in the index. To use a wildcard projection, set your index field name to $**. This directs Atlas to use all fields in the document (excluding _id).

For example:

Consider the following wildcard projection document:

{
  "product_attributes.elements" : 1,
  "product_attributes.resistance" : 1
}

If your index field name is $**, your index only includes the values of the fields in that projection.

Create a Wildcard Index

Use custom collation

Create a custom collation for the index by typing or pasting the collation document in the text box.

Collation Document

Create sparse index

Index skips over any document that is missing the indexed field.

Sparse Indexes

Build in rolling process

Can minimize the performance impact of index builds.

Rolling index builds succeed only when they meet certain conditions. To ensure your index build succeeds, avoid the following design patterns that commonly trigger a restart loop:

Index key exceeds the index key limit
Index name already exists
Index on more than one array field
Index on collection that has the maximum number of text indexes
Text index on collection that has the maximum number of text indexes

You can only build rolling indexes on M10+ Clusters.

Rolling Index Builds

Click Create Index.

Atlas Search and Atlas Vector Search Indexes

You can't create Atlas Search or Atlas Vector Search indexes in Data Explorer. To manage Atlas Search and Atlas Vector Search indexes for your collection, see:

Create a Wildcard Index

You can create wildcard indexes to support queries against unknown or arbitrary fields. To create a wildcard index in Atlas, manually type the wildcard index field (<field>.$**) into the Select a field name input.

Example

Consider a collection where documents contain a userMetadata object. The fields within the userMetadata object may vary between documents.

You can create a wildcard index on userMetadata to account for all potential fields within the object. Type the following into the Select a field name input:

userMetadata.$**

Specify a type (ascending or descending) for your wildcard index, then click Create Index.

Atlas shows the type of your new index as Wildcard.

Hide or Unhide an Index

You can hide an index from the query planner to evaluate the potential impact of dropping an index without actually dropping the index.

Hover over the index.

From the Indexes tab, hover over the index you want to hide.

Click the Hide Index button.

Click the closed-eye icon on the right that appears when you hover over your selected index.

Click Confirm.

In the dialog box, confirm the index you want to hide. After you confirm your selection, a Hidden badge appears under the Properties column.

To unhide your index, repeat steps 1-3. After you unhide your index, Atlas removes the Hidden badge from the Properties column.

Drop an Index

Click the trash can icon for the index to drop.

From the Indexes tab, to delete an index, click on the trash can icon for that index. A confirmation dialog appears.

Confirm the index to delete.

In the dialog, enter the name of the index to delete.

Click Drop to drop the index.

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