setDefaultRWConcern

Replica Sets复制集

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

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分片状群集

Issue the setDefaultRWConcern against a mongos in the cluster. 针对集群中的mongos发出setDefaultRWConcern。The mongos persists the updated settings to the config server replica set (CSRS). mongos将更新的设置保存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定期针对CSRS发出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“过时”的全局默认值副本。

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writeConcern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问题设置的情况下对mongos发出操作时，mongos将应用相应的全局默认设置。

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

Access Control访问控制

For replica sets or sharded clusters enforcing Authentication, setDefaultRWConcern requires that the authenticated user have the setDefaultRWConcern privilege action.对于实施身份验证的副本集或分片化集群，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：

• 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设置全局默认读取问题

The following operation sets the global read concern to "majority":以下操作将全局读取关注点设置为"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设置全局默认读写问题

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问题设置为：

• w: 2 write concern写入关注
• level: "majority" read concern.读取关注。

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未设置全局默认读写问题

Consider a deployment with the following default read and write concern:考虑具有以下默认读写问题的部署：

{
  "defaultWriteConcern" : {
    "w" : "majority"
  },
  "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)
}

The following operation unsets the global default read and write concern settings:以下操作将取消设置全局默认读写问题设置：

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

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：

{
  "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)
}