dropDatabase

Locks

Starting in version 4.2.2, the operation takes an exclusive (X) database lock only.

In versions 3.6-4.2.1, the operation takes an exclusive (X) database lock while dropping the collections in the database but a global lock when dropping the now-empty database.

User Management

This command does not delete the users associated with the current database. To drop the associated users, run the dropAllUsersFromDatabase command in the database you are deleting.

Indexes

Starting in MongoDB 4.4, the db.dropDatabase() method and dropDatabase command abort any in-progress index builds on collections in the target database before dropping the database. Aborting an index build has the same effect as dropping the built index. Prior to MongoDB 4.4, attempting to drop a database that contains a collection with an in-progress index build results in an error, and the database is not dropped.

For replica sets or shard replica sets, aborting an index on the primary does not simultaneously abort secondary index builds. MongoDB attempts to abort the in-progress builds for the specified indexes on the primary and if successful creates an associated abort oplog entry. Secondary members with replicated in-progress builds wait for a commit or abort oplog entry from the primary before either committing or aborting the index build.

Replica Set and Sharded Clusters

Replica Sets

At minimum, dropDatabase waits until all collections drops in the database have propagated to a majority of the replica set members (i.e. uses the write concern "majority").

If you specify a write concern that requires acknowledgement from fewer than the majority, the command uses write concern "majority".

If you specify a write concern that requires acknowledgement from more than the majority, the command uses the specified write concern.

Sharded Clusters

When issued on a sharded cluster, MongoDB converts the specified write concern to "majority".

If you intend to create a new database with the same name as the dropped database, you must follow these additional steps for using the dropDatabase command, specific to your version of MongoDB:

• For MongoDB 4.4 and later, you must:

  1. Run the dropDatabase command on a mongos.

  2. Once the command successfully completes, run the dropDatabase command once more on a mongos.

• For MongoDB 4.2, you must:

  1. Run the dropDatabase command on a mongos.

  2. Once the command successfully completes, run the dropDatabase command once more on a mongos.

  3. Use the flushRouterConfig command on all mongos instances before reading or writing to that database.

• For MongoDB 4.0 and earlier, you must:

  1. Run the dropDatabase command on a mongos.

  2. Connect to each shard's primary and verify that the namespace has been dropped. If it has not, rerun the dropDatabase command again directly from the primary.

  3. Connect to a mongos, switch to the config database, and remove any reference to the removed namespace from the databases, collections, chunks, tags, and locks collections:

     use config
     db.collections.remove( { _id: /^DATABASE\./ }, {writeConcern: {w: 'majority' }} )
     db.databases.remove( { _id: "DATABASE" }, {writeConcern: {w: 'majority' }} )
     db.chunks.remove( { ns: /^DATABASE\./ }, {writeConcern: {w: 'majority' }} )
     db.tags.remove( { ns: /^DATABASE\./ }, {writeConcern: {w: 'majority' }} )
     db.locks.remove( { _id: /^DATABASE\./ }, {writeConcern: {w: 'majority' }} )

     Where DATABASE represents the namespace of the database you just dropped.

  4. Connect to the primary of each shard, and remove any reference to the removed namespace from the cache.databases, cache.collections, and cache.chunks.DATABASE.COLLECTION collections:

     db.getSiblingDB("config").cache.databases.remove({_id:"DATABASE"}, {writeConcern: {w: 'majority' }});
     db.getSiblingDB("config").cache.collections.remove({_id:/^DATABASE.*/}, {writeConcern: {w: 'majority' }});
     db.getSiblingDB("config").getCollectionNames().forEach(function(y) {
        if(y.indexOf("cache.chunks.DATABASE.") == 0)
         db.getSiblingDB("config").getCollection(y).drop()
      })

     Where DATABASE represents the namespace of the database you just dropped.

  5. Use the flushRouterConfig command on all mongos instances before reading or writing to that database.

These steps ensure that all cluster nodes refresh their metadata cache, which includes the location of the primary shard for the new database. Otherwise, you may miss data on reads, and may not write data to the correct shard. To recover, you must manually intervene.

Change Streams

The db.dropDatabase() method and dropDatabase create an invalidate for any Change Streams opened on the dropped database or opened on the collections in the dropped database.