Definition
balancerStartNew in version 3.4.
Starts the balancer thread. The command does not wait for a balancing round to start.
Starting in MongoDB 4.2, the command enables auto-splitting for the sharded cluster. To disable auto-splitting when the balancer is enabled, you can use
sh.disableAutoSplit().Tip
In
mongosh, this command can also be run through thesh.startBalancer()helper method.Helper methods are convenient for
mongoshusers, 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.In MongoDB versions earlier than 6.1, the command enables auto-splitting for the sharded cluster. To disable auto-splitting when the balancer is enabled, you can use
sh.disableAutoSplit().
Compatibility
This command is available in deployments hosted in the following environments:
MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud
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
You can only issue the
balancerStart against the admin database on a
mongos instance.
The command takes the following form:
db.adminCommand( { balancerStart: 1, maxTimeMS: <number> } )
Field | Type | Description |
|---|---|---|
| any | Any value. |
| integer | Optional. Time limit for enabling the balancer. Defaults to 60000 milliseconds. Changed in version 3.4: If using the 3.4 |
Example
To start the balancer thread, connect to a mongos instance
and issue the following command:
db.adminCommand( { balancerStart: 1 } )