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Mongo.getWriteConcern()

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Definition定义

Mongo.getWriteConcern()
Returns:返回值：The current write concern for the Mongo() connection object.Mongo()连接对象的当前写入关注。

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().getWriteConcern()

This operation returns a document with the following values:此操作返回具有以下值的文档：

{ w: <value>, wtimeout: <number>, j: <boolean> }

The fields are:

Field字段Description描述
wThe number of mongod or mongod instances that must acknowledge a write. Possible values are: 必须确认写入的mongod或mongod实例数。可能的值为：
  • "majority". A majority of the target instances must acknowledge the write.大多数目标实例必须确认写入。
  • <number>. The specified number of target instances must acknowledge the write.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.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.仅当w的值大于1时才适用。

Example实例

To return the current write concern, enter the following:要返回当前写入关注，请输入以下内容：

db.getMongo().getWriteConcern()

When a write concern is specified using Mongo.setWriteConcern(), the output of Mongo.getWriteConcern() is similar to:当使用Mongo.setWriteConcern()指定写入关注时，Mongo.getWriteConcern()的输出类似于：

WriteConcern { w: 2, wtimeout: 1000, j: true }

The Mongo.getWriteConcern() command returns an empty line if no write concern has been specified.如果没有指定写入关注，Mongo.getWriteConcern()命令将返回一行空行。

Tip

See also: 另请参阅：