enableSharding
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Definition
enableShardingNote
Changed in version 6.0.
Starting in MongoDB 6.0, this command is not required to shard a collection.
The
enableShardingcommand explicitly creates a database.Tip
In
mongosh, this command can also be run through thesh.enableSharding()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.
Syntax
The command has the following syntax:
Recommended. Specify the database to create:
db.adminCommand( { enableSharding: "<database name>" } ) Optionally, starting in MongoDB 4.2.2 (and 4.0.14), you can include the primary shard specification in the command, although this is not recommended:
db.adminCommand( { enableSharding: "<database name>", primaryShard: "<shard name>" // Available starting in MongoDB 4.2.2 (and 4.0.14) } )
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 |
|---|---|---|
String | The database you want to use. The database is created if it does not exist. | |
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. WarningTipIn general, you should not need to specify the primary shard. Allow the balancer to select the primary shard instead. Available starting in MongoDB 4.2.2 (and 4.0.14) |
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" } )