setDefaultRWConcern (database command数据库命令)

Replica Sets副本集

Issue setDefaultRWConcern against the replica set primary. 对primary副本集发出setDefaultRWConcern。The primary replicates the new global default settings to the remaining members of the replica set. Secondaries which have not yet replicated the updated global default settings continue using their local 'stale' copy of the defaults.主服务器将新的全局默认设置复制到副本集的其余成员。尚未复制更新的全局默认设置的借调人员继续使用其本地默认设置的“过时”副本。

Issue the setDefaultRWConcern command with a writeConcern of w : "majority" to ensure the command only returns after the changes have propagated to a majority of replica set members.发出writeConcern为w : "majority"的setDefaultRWConcern命令，以确保该命令仅在更改传播到大多数副本集成员后返回。

Sharded Clusters分片集群

Issue the setDefaultRWConcern against a mongos in the cluster. 对集群中的mongos发出setDefaultRWConcern。The mongos persists the updated settings to the config server replica set (CSRS). mongos将更新的设置持久化到配置服务器副本集（CSRS）。Each mongos periodically issues a getDefaultRWConcern against the CSRS to refresh their local copy of the global settings. 每个mongo都会定期向CSRS发出一个getDefaultRWConcern，以刷新其全局设置的本地副本。A mongos uses its local 'stale' copy of the global defaults during the time period between refreshes.mongos在刷新之间的时间段内使用其本地全局默认值的“过时”副本。

Issue the setDefaultRWConcern command with a writeConcern of w : "majority" to ensure the command only returns after the changes have propagated to a majority of CSRS members.发出带有w : "majority"的setDefaultRWConcern命令，以确保该命令仅在更改传播到大多数CSRS成员后返回。

When an application issues an operation against the mongos without explicitly specifying a read or write concern setting, the mongos applies the corresponding global default setting.当应用程序在没有明确指定读或写关注设置的情况下对mongos发出操作时，mongos会应用相应的全局默认设置。

The global default settings do not propagate to the individual shards. You cannot run setDefaultRWConcern against a shard.全局默认设置不会传播到单个分片。您不能对分片运行setDefaultRWConcern。

Access Control访问控制

For replica sets or sharded clusters enforcing Authentication on Self-Managed Deployments, setDefaultRWConcern requires that the authenticated user have the setDefaultRWConcern privilege action.对于在自我管理部署上强制执行身份验证的副本集或分片集群，setDefaultRWConcern要求经过身份验证的用户具有setDefaultRWConcern权限操作。

The clusterManager built-in role provides the required privileges to run setDefaultRWConcern.clusterManager内置角色提供运行setDefaultRWConcern所需的权限。

Set Global Default Write Concern设置全局默认写入关注

The following operation sets the global write concern to the following:以下操作将全局写入关注设置为以下内容：

• w: 2

db.adminCommand({
  "setDefaultRWConcern" : 1,
  "defaultWriteConcern" : {
    "w" : 2
  }
})

The operation returns a document similar to the following:该操作返回一个类似于以下内容的文档：

{
  "defaultWriteConcern" : {
   "w" : 2
  },
  "updateOpTime" : Timestamp(1586290895, 1),
  "updateWallClockTime" : ISODate("2020-04-07T20:21:41.849Z"),
  "localUpdateWallClockTime" : ISODate("2020-04-07T20:21:41.862Z"),
  "ok" : 1,
  "$clusterTime" : { ... }
  "operationTime" : Timestamp(1586290925, 1)
}

Set Global Default Read Concern设置全局默认读取关注

The following operation sets the global read concern to "majority":以下操作将全局读取关注设置为"majority"：

db.adminCommand({
  "setDefaultRWConcern" : 1,
  "defaultReadConcern" : { "level" : "majority" }
})

The operation returns a document similar to the following:该操作返回一个类似于以下内容的文档：

{
  "defaultReadConcern" : {
    "level" : "majority"
  },
  "updateOpTime" : Timestamp(1586290895, 1),
  "updateWallClockTime" : ISODate("2020-04-07T20:21:41.849Z"),
  "localUpdateWallClockTime" : ISODate("2020-04-07T20:21:41.862Z"),
  "ok" : 1,
  "$clusterTime" : { ... }
  "operationTime" : Timestamp(1586290925, 1)
}

Set Global Default Read and Write Concern设置全局默认读写入关注

The following operation sets the global default read and write concern to the following:以下操作将全局默认读写入关注设置为以下内容：

• w: 2 write concern
• level: "majority" read concern.

db.adminCommand({
  "setDefaultRWConcern" : 1,
  "defaultWriteConcern" : {
    "w" : 2
  },
  "defaultReadConcern" : { "level" : "majority" }
})

The operation returns a document similar to the following:该操作返回一个类似于以下内容的文档：

"defaultWriteConcern" : {
  "w" : 2
},
"defaultReadConcern" : {
  "level" : "majority"
}

Unset Global Default Read and Write Concern取消设置全局默认读写入关注

You can:你可以：

• Unset the global default read concern.取消设置全局默认读取关注。
• Only unset the global default write concern if you haven't already set it.只有当您尚未设置全局默认写入关注时，才取消设置它。

For example, assume the global default read concern is set to level: "majority". To unset the global default read concern, use an empty document {}:例如，假设全局默认读取关注设置为level: "majority"。要取消设置全局默认读取关注，请使用空文档{}：

db.adminCommand( {
   "setDefaultRWConcern" : 1,
   "defaultReadConcern" : {}
} )

The operation returns a document that indicates the operation was successful:该操作返回一个文档，指示操作成功：

{
   defaultReadConcern: { level: 'local' },
   defaultWriteConcern: { w: 2, wtimeout: 0 },
   updateOpTime: Timestamp({ t: 1656696934, i: 1 }),
   updateWallClockTime: ISODate("2022-07-01T17:35:40.578Z"),
   defaultWriteConcernSource: 'global',
   defaultReadConcernSource: 'implicit',
   localUpdateWallClockTime: ISODate("2022-07-01T17:35:40.578Z"),
   ok: 1,
   '$clusterTime': {
      ...
   },
   operationTime: Timestamp({ t: 1656632593, i: 1 })
}

You can only unset the global default write concern if you haven't already set it.如果尚未设置全局默认写入关注，则只能取消设置它。

To unset the global default write concern, use an empty document {}:要取消设置全局默认写入关注，请使用空文档{}：

db.adminCommand( {
   "setDefaultRWConcern" : 1,
   "defaultWriteConcern" : {}
} )

If the global default write concern is:如果全局默认写入关注是：

• Unset, the operation succeeds.取消设置，操作成功。
• Already set, the operation returns the following error.已设置，操作返回以下错误。

MongoServerError: The global default write concern cannot be unset
once it is set.