Definition
balancerStart
Starts the balancer thread. The command does not wait for a balancing round to start.
Starting in MongoDB 7.0, starting the balancer also enables the AutoMerger for the sharded cluster.
Tip
In
mongosh
, this command can also be run through thesh.startBalancer()
helper method.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
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 has the following syntax:
db.adminCommand( { balancerStart: 1, maxTimeMS: <number> } )
Command Fields
Field | Type | Description |
---|---|---|
| any | Any value. |
| integer | Optional. Time limit for enabling the balancer. Defaults to 60000 milliseconds. |
Example
To start the balancer thread, connect to a mongos
instance
and issue the following command:
db.adminCommand( { balancerStart: 1 } )