dropIndexes

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Compatibility

Syntax
Command Fields
Behavior
Examples

dropIndexes: Changed in version 5.0.
The dropIndexes command drops one or more indexes (except the index on the _id field and the last remaining shard key index, if one exists) from the specified collection.
Tip
In mongosh, this command can also be run through the db.collection.dropIndex() and db.collection.dropIndexes() helper methods..
Helper methods are convenient for mongosh users, but they may not return the same level of information as database commands. In cases where the convenience is not needed or the additional return fields are required, use the database command.

Compatibility

This command is available in deployments hosted in the following environments:

MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

Note

This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see Unsupported Commands.

MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

Syntax

The command has the following syntax:

{ dropIndexes: <string>, index: <string|document|arrayofstrings>, writeConcern: <document>, comment: <any> }

Command Fields

The command takes the following fields:

Field	Type	Description
dropIndexes	String	The name of the collection whose indexes to drop.
index	string or document or array of strings	The index or indexes to drop. To drop all indexes except the `_id` index and the last remaining shard key index from the collection if one exists, specify `"*"`. To drop a single index, specify either the index name, the index specification document (unless the index is a text index), or an array of the index name. To drop a text index, specify the index names instead of the index specification document. If this index is the last remaining shard key index, `dropIndexes` raises an error. To drop multiple indexes, specify an array of the index names.
writeConcern	document	Optional. A document expressing the write concern of the `drop` command. Omit to use the default write concern.
`comment`	any	Optional. A user-provided comment to attach to this command. Once set, this comment appears alongside records of this command in the following locations: mongod log messages, in the `attr.command.cursor.comment` field. Database profiler output, in the `command.comment` field. `currentOp` output, in the `command.comment` field. A comment can be any valid BSON type (string, integer, object, array, etc).

Behavior

Starting in MongoDB 5.0, dropIndexes raises an error if you attempt to use it to remove the last remaining shard key compatible index. Passing "*" to dropIndexes drops all indexes except the _id index and the last remaining shard key compatible index, if one exists.

Kill related queries only

The dropIndexes operation only kills queries that are using the index being dropped. This may include queries considering the index as part of query planning.

Resource Locking

dropIndexes obtains an exclusive lock on the specified collection for the duration of the operation. All subsequent operations on the collection must wait until dropIndexes releases the lock.

Index Names

If the method is passed an array of index names that includes a non-existent index, the method errors without dropping any of the specified indexes.

`_id` Index

You cannot drop the default index on the _id field.

text Indexes

To drop a text index, specify the index name instead of the index specification document.

Abort In-Progress Index Builds

New in version 4.4: If an index specified to dropIndexes is still building, dropIndexes attempts to abort the in-progress build. Aborting an index build has the same effect as dropping the built index. Prior to MongoDB 4.4, dropIndexes would return an error if the collection had any in-progress index builds.

For replica sets, run dropIndexes on the primary. The primary aborts the index build and creates an associated "abortIndexBuild" oplog entry. Secondaries which replicate the "abortIndexBuild" oplog entry abort the in-progress index build and discard the build job. See Index Build Process for detailed documentation on the index build process and the specific timing for terminating an in-progress index build.

The indexes specified to dropIndexes must be the entire set of in-progress builds associated to a single createIndexes or db.collection.createIndexes() operation. To drop a specific index out of a set of related in-progress builds, wait until the index builds complete and specify that index to dropIndexes.

For example, a createIndexes / createIndexes() operation creates three indexes. Assuming all three index builds are in-progress, dropIndexes must specify all three indexes to abort the index builds.

Use currentOp to identify the index builds associated to a createIndexes / createIndexes() operation. See Active Indexing Operations for an example.

Hidden Indexes

MongoDB offers the ability to hide or unhide indexes from the query planner. By hiding an index from the planner, you can evaluate the potential impact of dropping an index without actually dropping the index.

If after the evaluation, the user decides to drop the index, you can drop the hidden index; i.e. you do not need to unhide it first to drop it.

If, however, the impact is negative, the user can unhide the index instead of having to recreate a dropped index. And because indexes are fully maintained while hidden, the indexes are immediately available for use once unhidden.

For more information on hidden indexes, see Hidden Indexes.

Examples

To drop all non-_id indexes , specify "*" for the index.
```
db.runCommand( { dropIndexes: "collection", index: "*" } )
```
To drop a single index, issue the command by specifying the name of the index you want to drop. For example, to drop the index named age_1, use the following command:
```
db.runCommand( { dropIndexes: "collection", index: "age_1" })
```
mongosh provides the helper methods db.collection.dropIndex() and db.collection.dropIndexes():
```
db.collection.dropIndex("age_1");
```
To drop multiple indexes, issue the command by specifying an array of the index names:
```
db.runCommand( { dropIndexes: "collection", index: [ "age_1", "age_1_status_1" ] } )
```

Tip