MongoDB Remove All Indexes from the Database

In this post, we will explore how to use the dropIndexes() method in MongoDB Shell to remove an index from a given collection. We will also build a simple script to remove all the indexes from a given collection.

Let’s dive in.

MongoDB Db.Collection.DropIndexes()

To drop a specific index from a collection, we use the dropIndexes() method and pass the target index that you wish to remove from the collection.

You can specify the index name if it’s a text index or the index specification document otherwise.

Example 1: Drop an Index by Name

In the following example query, we can use the dropIndexes() method to drop an index under the name, “type”.

ent> db.netflix.dropIndexes("type")

The given command removes the index with the name, “type”. Dropping an index by name is supported for text index types.

The query returns an output as follows:

{ nIndexesWas: 4, ok: 1 }

Example 2: Drop Multiple Indexes by Name

We can also remove multiple indexes using their names as shown in the following example query:

db.netflix.dropIndexes("year", "rating")

In this case, the command should remove the “year” and “rating” indexes from the collection.

Output:

{ nIndexesWas: 3, ok: 1 }

Example 3: Drop All Indexes Except the _id Index

The following example query shows how to use the dropIndexes() method to drop all the indexes from a given collection except the _id index.

db.netflix.dropIndexes()

The command should remove all the non _id indexes from the collection as shown in the following output:

{
nIndexesWas: 4,
msg: 'non-_id indexes dropped for collection',
ok: 1
}

Example 4: Drop All Indexes from a Given Database

If we wish to remove all the indexes from a given database, we can use a simple script as shown in the following example:

db.getCollectionNames().forEach(function(collectionName) {
... db.runCommand({dropIndexes: collectionName, index: "*"});
... });

The previous command uses the forEach function to iterate over each collection in the database. It then passes each collection to the dropIndexes command and the target index as a wildcard character.

This should allow you to remove all the non _id indexes from the database in a simple step.

Conclusion

In this post, we discussed how to use the dropIndexes method in the MongoDB Shell to remove one or multiple indexes from a collection.