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Mongo.setWriteConcern()

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Definition定义

Mongo.setWriteConcern()

Sets the write concern for the Mongo() connection object.设置Mongo()连接对象的写入关注。

See the Write Concern for an introduction to write concerns in MongoDB.有关在MongoDB中编写关注的介绍，请参阅写入关注。

Syntax语法

The command takes the following form:该命令采用以下形式：

db.getMongo().setWriteConcern( { w: <value>, j: <boolean>, wtimeout: <number> } )

The fields are:字段为：

Field字段Description描述
wThe number of mongod or mongod instances that must acknowledge a write. 必须确认写入的mongod或mongod实例数。Possible values are: 可能的值为：
  • "majority". A majority of the target instances must acknowledge the write."majority"。大多数目标实例必须确认写入。
  • <number>. The specified number of target instances must acknowledge the write.<number>。指定数量的目标实例必须确认写入。
  • <custom write concern name>. A user defined write concern, the tagged instances must acknowledge the write.<custom write concern name>。对于用户定义的写入关注，标记的实例必须确认写入。
See write concern specification for details. 有关详细信息，请参阅写入关注规范。
jA boolean value. 布尔值。j: true requests acknowledgment that the write operation has been written to the on-disk journal.请求确认写入操作已写入磁盘上的日志。
wtimeoutThe number of milliseconds to wait for acknowledgement of the write concern. 等待确认写入关注的毫秒数。wtimeout is only applicable when w has a value greater than 1.只有当w的值大于1时，wtimeout才适用。

Example实例

In the following example:在以下示例中：

  • Two mongod or mongod instances must acknowledge writes.两个mongod或mongod实例必须确认写入。
  • There is a 1 second timeout to wait for write acknowledgements.有1秒的超时等待写入确认。
db.getMongo().setWriteConcern( { w: 2, wtimeout: 1000 } )
Tip

See also: 另请参阅：