> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

# db.collection.dropIndex() (mongosh method)

## Definition

Drops or removes the specified index from a collection.

**Note:**

- You cannot drop the default index on the `_id` field.

- You cannot specify [`db.collection.dropIndex("*")`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) to drop all non-`_id` indexes. Use [`db.collection.dropIndexes()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindexes.md#mongodb-method-db.collection.dropIndexes) instead.

To get the index name or the index specification document for the [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) method, use the [`db.collection.getIndexes()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.getindexes.md#mongodb-method-db.collection.getIndexes) method.

### Parameters

The [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) method takes the following parameter:

| Parameter | Type | Description |
| --- | --- | --- |
| `index` | string or document | Required. Specifies the index to drop. You can specify the index either by the index name or by the index specification document. To drop a [text](https://www.mongodb.com/docs/manual/core/indexes/index-types/index-text.md#std-label-index-type-text) index, specify the index name. You cannot specify `"*"` to drop all non-`_id` indexes. Use [`db.collection.dropIndexes()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindexes.md#mongodb-method-db.collection.dropIndexes) instead. If an index specified to [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) is still building, [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) attempts to stop the in-progress build. Stopping an index build has the same effect as dropping the built index. See [Stop In-Progress Index Builds](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#std-label-dropIndex-method-index-builds) for more complete documentation. |

## Compatibility

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

- [MongoDB Atlas](https://www.mongodb.com/docs/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.](https://www.mongodb.com/docs/atlas/unsupported-commands/)

- [MongoDB Enterprise](https://www.mongodb.com/docs/manual/administration/install-enterprise.md#std-label-install-mdb-enterprise): The subscription-based, self-managed version of MongoDB

- [MongoDB Community](https://www.mongodb.com/docs/manual/administration/install-community.md#std-label-install-mdb-community-edition): The source-available, free-to-use, and self-managed version of MongoDB

## Behavior

Starting in MongoDB 8.3, [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) is idempotent. If you specify an index that does not exist, [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) ignores the non-existent index and completes successfully instead of returning an `IndexNotFound` error. In earlier versions, [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) returns an `IndexNotFound` error if the specified index does not exist.

You can use [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) to drop existing indexes on the same collection even if there is a build in progress on another index. In earlier versions, attempting to drop a different index during an in-progress index build results in a `BackgroundOperationInProgressForNamespace` error.

### Resource Locking

[`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) obtains an exclusive lock on the specified collection for the duration of the operation. All subsequent operations on the collection must wait until [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) releases the lock.

### Stop In-Progress Index Builds

If an index specified to [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) is still building, [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) attempts to stop the in-progress build. Stopping an index build has the same effect as dropping the built index.

For replica sets, run [`db.collection.dropIndex()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.dropindex.md#mongodb-method-db.collection.dropIndex) on the [primary](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-primary). The primary stops the index build and creates an associated "abortIndexBuild" [oplog](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-oplog) entry. Secondaries which replicate the "abortIndexBuild" oplog entry stop the in-progress index build and discard the build job. See [Index Build Process](https://www.mongodb.com/docs/manual/core/index-creation.md#std-label-index-build-process) for detailed documentation on the index build process.

Use [`currentOp`](https://www.mongodb.com/docs/manual/reference/command/currentop.md#mongodb-dbcommand-dbcmd.currentOp) to identify the index builds associated with a [`createIndexes`](https://www.mongodb.com/docs/manual/reference/command/createindexes.md#mongodb-dbcommand-dbcmd.createIndexes) or [`db.collection.createIndexes()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.createindexes.md#mongodb-method-db.collection.createIndexes) operation. See [Active Indexing Operations](https://www.mongodb.com/docs/manual/reference/command/currentop.md#std-label-currentOp-cmd-index-creation) 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.](https://www.mongodb.com/docs/manual/core/index-hidden.md)

## Example

In a `pets` collection, create a descending index on the `cat` field:

```javascript
db.pets.createIndex( { cat: -1 }, { name: "catIdx" } )
```

To see the indexes in the `pets` collection, run the [`getIndexes()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.getindexes.md#mongodb-method-db.collection.getIndexes) method:

```javascript
db.pets.getIndexes()
```

**Output:**

```text
[
   { v: 2, key: { _id: 1 }, name: '_id_' },
   { v: 2, key: { cat: -1 }, name: 'catIdx' }
]
```

The single field index on the field `cat` has the user-specified name of `catIdx` and the index specification document of `{ "cat" : -1 }`.

To drop the index `catIdx`, you can use either the index name:

```javascript
db.pets.dropIndex( "catIdx" )
```

Or you can use the index specification document `{ "cat" : -1 }`:

```javascript
db.pets.dropIndex( { "cat" : -1 } )
```

The `dropIndex` command returns the number of indexes in the collection prior to the command being run, and indicates whether the command was successful:

```javascript
{ nIndexesWas: 2, ok: 1 }
```

To confirm that the index was dropped, run the `getIndexes()` method again:

```javascript
db.pets.getIndexes()
```

**Output:**

```text
[ { v: 2, key: { _id: 1 }, name: '_id_' } ]
```