Mongo.startSession() (mongosh method方法)

Definition定义

Mongo.startSession(<options>)

Starts a session for the connection. mongosh assigns the session ID to commands associated with the session.启动连接会话。mongosh将会话ID分配给与会话关联的命令。

Important

mongosh Method方法

This page documents a mongosh method. This is not the documentation for database commands or language-specific drivers, such as Node.js.本页记录了一种mongosh方法。这不是数据库命令或特定语言驱动程序（如Node.js）的文档。

For the database command, see the startSession command.有关数据库命令，请参阅startSession命令。

For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.有关MongoDB API驱动程序，请参阅特定语言的MongoDB驱动程序文档。

A session can only be used with the MongoClient object that created the session. A single session cannot be used concurrently. Operations that use a single session must be run sequentially.会话只能与创建会话的MongoClient对象一起使用。单个会话不能同时使用。使用单个会话的操作必须按顺序运行。

The startSession() method can take a document with session options. The options available are:startSession()方法可以接收带有会话选项的文档。可用的选项有：

Field字段	Description描述
causalConsistency	Boolean. Enables or disables causal consistency for the session. 布尔值。启用或禁用会话的因果一致性。Mongo.startSession() enables causalConsistency by default. Mutually exclusive with snapshot.默认情况下启用causalConsistency。与snapshot相互排斥。 After starting a session, you cannot modify its causalConsistency setting.启动会话后，您无法修改其causalConsistency设置。 The session may have causal consistency enabled even though the Mongo() connection object may have causal consistency disabled or vice versa. 即使Mongo()连接对象可能禁用因果一致性，会话也可能启用因果一致性；反之亦然。To set causal consistency on the connection object, see Mongo.setCausalConsistency().要在连接对象上设置因果一致性，请参阅Mongo.setCausalConsistency()。
readConcern	Document. Specifies the read concern.文档。指定读取关注。 To modify the setting after starting a session, see Session.getOptions().setReadConcern().要在启动会话后修改设置，请参阅Session.getOptions().setReadConcern()。
readPreference	Document. Specifies the read preference.文档。指定读取首选项。 The readPreference document contains the mode field and the optional tags field:readPreference文档包含mode字段和可选tags 字段： { mode: <string>, tags: <array> } To modify the setting after starting a session, see Session.getOptions().setReadPreference().要在启动会话后修改设置，请参阅Session.getOptions().setReadPreference()。
retryWrites	Boolean. Enables or disables the ability to retry writes upon encountering transient network errors.布尔值。启用或禁用在遇到瞬态网络错误时重试写入的能力。 If you start mongosh with the --retryWrites option, retryWrites is enabled by default for Mongo.startSession().如果您使用--retryWrites选项启动mongosh，则默认情况下Mongo.startSession()会启用retryWrites。 After starting a session, you cannot modify its retryWrites setting.启动会话后，您无法修改其retryWrites设置。
snapshot	Boolean. Enables snapshot reads for the session for MongoDB 5.0+ deployments. Mutually exclusive with causalConsistency.布尔值。为MongoDB 5.0+部署启用会话快照读取。与causalConsistency相互排斥。
writeConcern	Document. Specifies the write concern.文件。指定写入关注。 To modify the setting after starting a session, see Session.getOptions().setWriteConcern().要在启动会话后修改设置，请参阅Session.getOptions().setWriteConcern()。

Compatibility兼容性

This method is available in deployments hosted in the following environments:此方法在以下环境中托管的部署中可用：

• MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud：云中MongoDB部署的完全托管服务

• MongoDB Enterprise: The subscription-based, self-managed version of MongoDB：MongoDB的基于订阅的自我管理版本
• MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB：MongoDB的源代码可用、免费使用和自我管理版本

Examples示例

The following starts a session with causal consistency and retryable writes enabled on the Mongo() connection object associated with mongosh's global db variable:下面开始一个会话，在与mongosh的全局db变量关联的Mongo()连接对象上启用因果一致性和可重试写入：

db = db.getMongo().startSession({retryWrites: true, causalConsistency: true}).getDatabase(db.getName());