enableSharding

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Definition

Compatibility
Syntax
Command Fields
Behavior
Example

Definition

enableSharding: Note
Changed in version 6.0.
Starting in MongoDB 6.0, this command is not required to shard a collection.
The enableSharding command explicitly creates a database.
Tip
In mongosh, this command can also be run through the sh.enableSharding() 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

Important

This command is not supported in serverless instances. For more information, see Unsupported Commands.

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

The command has the following syntax:

Recommended. Specify the database to create:
```
db.adminCommand(
   {
     enableSharding: "<database name>"
   }
)
```
Optionally, you can include the primary shard specification in the command, although this is not recommended:
```
db.adminCommand(
   {
     enableSharding: "<database name>",
     primaryShard: "<shard name>"
   }
)
```

You can only run the enableSharding command on the admin database from a mongos instance.

Command Fields

The command takes the following fields:

Field	Type	Description
enableSharding	String	The database you want to use. The database is created if it does not exist.
primaryShard	String	Optional. The primary shard for the database; the primary shard contains the unsharded collection for this database. In general, rather than explicitly specifying the primary shard, it is recommended to let the balancer select the primary shard instead. Warning Tip In general, you should not need to specify the primary shard. Allow the balancer to select the primary shard instead.

Returns

The command returns a document that contains status of the operation.

Behavior

Write Concern

mongos uses "majority" for the enableSharding command and its helper sh.enableSharding().

Primary Shard

In general, you should not need to specify the primaryShard in the command. Instead, allow the balancer to select the primary shard.

However, if you do specify the primaryShard in the command for a database and the database is already sharding enabled with a different primary shard, the operation returns an error and the primary shard for the database remains as before. To change the primary shard for a database, use movePrimary instead.

Example

The following command, run from a mongos, creates the the shardTest database:

db.adminCommand( { enableSharding: "shardTest" } )