enableSharding

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Definition定义

enableSharding

The enableSharding command enables sharding on the specified database. Once you enabled sharding for a database, you can use the shardCollection command to shard collections in that database.

The mongo shell method sh.enableSharding() wraps the enableSharding command.

Syntax语法

The enableSharding command has the following syntax:语法如下所示：

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

Fields

The command takes the following fields:

Field字段Type类型Description描述
enableSharding String

The database for which you wish to enable sharding.

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.

Tip

In 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行为

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示例

The following command, run from a mongos, enables sharding for the test database:

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

To verify, run sh.status().

See also参阅