sh.enableSharding()

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Definition定义

sh.enableSharding(database, primaryShard)

Enables sharding on the specified database. Once you enabled sharding for a database, you can use sh.shardCollection() to shard collections in that database. The mongo shell method sh.enableSharding() wraps the enableSharding command.

Syntax语法

The sh.enableSharding has the following form:

sh.enableSharding(
   <database>,
   <primary shard>  // Optional. Available starting in MongoDB 4.2.2 (and 4.0.14)
)

Parameter

The sh.enableSharding() method takes the following parameter:

Parameter参数Type类型Description描述
database 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)

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 primary shard for a database and the database is already enabled for sharding 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 the movePrimary command instead.

Example示例

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

sh.enableSharding("test")

To verify, run sh.status().

See also参阅