Session.commitTransaction()

Definition定义

Session.commitTransaction()

Saves the changes made by the operations in the multi-document transaction and ends the transaction.保存多文档事务中的操作所做的更改并结束事务。

Important

mongosh Method

This page documents a mongosh method. This is not the documentation for database commands or language-specific drivers, such as Node.js.

For the database command, see the commitTransaction command.

For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.

For the legacy mongo shell documentation, refer to the documentation for the corresponding MongoDB Server release:

mongo shell v4.4

Changed in version 4.2.4.2版更改。Starting in MongoDB 4.2, multi-document transactions are available for both sharded clusters and replica sets.从MongoDB 4.2开始，多文档事务可用于分片集群和副本集。

Behavior行为

Example实例

Consider a scenario where as changes are made to an employee's record in the hr database, you want to ensure that the events collection in the reporting database are in sync with the hr changes. 考虑这样一种情况：当对hr数据库中的员工记录进行更改时，您希望确保reporting数据库中的events集合与hr更改同步。That is, you want to ensure that these writes are done as a single transaction, such that either both operations succeed or fail.也就是说，您希望确保这些写入是作为单个事务完成的，这样两个操作要么成功，要么失败。

The employees collection in the hr database has the following documents:hr数据库中的employees集合包含以下文档：

{ "_id" : ObjectId("5af0776263426f87dd69319a"), "employee" : 3, "name" : { "title" : "Mr.", "name" : "Iba Ochs" }, "status" : "Active", "department" : "ABC" }
{ "_id" : ObjectId("5af0776263426f87dd693198"), "employee" : 1, "name" : { "title" : "Miss", "name" : "Ann Thrope" }, "status" : "Active", "department" : "ABC" }
{ "_id" : ObjectId("5af0776263426f87dd693199"), "employee" : 2, "name" : { "title" : "Mrs.", "name" : "Eppie Delta" }, "status" : "Active", "department" : "XYZ" }

The events collection in the reporting database has the following documents:reporting数据库中的events集合包含以下文档：

{ "_id" : ObjectId("5af07daa051d92f02462644a"), "employee" : 1, "status" : { "new" : "Active", "old" : null }, "department" : { "new" : "ABC", "old" : null } }
{ "_id" : ObjectId("5af07daa051d92f02462644b"), "employee" : 2, "status" : { "new" : "Active", "old" : null }, "department" : { "new" : "XYZ", "old" : null } }
{ "_id" : ObjectId("5af07daa051d92f02462644c"), "employee" : 3, "status" : { "new" : "Active", "old" : null }, "department" : { "new" : "ABC", "old" : null } }

The following example opens a transaction, updates an employee's status to Inactive in the employees status and inserts a corresponding document to the events collection, and commits the two operations as a single transaction.以下示例打开一个事务，在员工状态中将员工的状态更新为Inactive，并将相应的文档插入到events集合中，然后将这两个操作作为单个事务提交。

// Runs the txnFunc and retries if TransientTransactionError encountered如果遇到TransientTransactionError，则运行txnFunc并重试

function runTransactionWithRetry(txnFunc, session) {
    while (true) {
        try {
            txnFunc(session);  // performs transaction执行事务
            break;
        } catch (error) {
            // If transient error, retry the whole transaction如果出现暂时错误，请重试整个事务
            if ( error.hasOwnProperty("errorLabels") && error.errorLabels.includes("TransientTransactionError")  ) {
                print("TransientTransactionError, retrying transaction ...");
                continue;
            } else {
                throw error;
            }
        }
    }
}

// Retries commit if UnknownTransactionCommitResult encountered如果遇到UnknownTransactionCommitResult，则重试提交

function commitWithRetry(session) {
    while (true) {
        try {
            session.commitTransaction(); // Uses write concern set at transaction start.在事务开始时使用写入关注集。
            print("Transaction committed.");
            break;
        } catch (error) {
            // Can retry commit可以重试提交
            if (error.hasOwnProperty("errorLabels") && error.errorLabels.includes("UnknownTransactionCommitResult") ) {
                print("UnknownTransactionCommitResult, retrying commit operation ...");
                continue;
            } else {
                print("Error during commit ...");
                throw error;
            }
       }
    }
}

// Updates two collections in a transactions更新事务记录中的两个集合

function updateEmployeeInfo(session) {
    employeesCollection = session.getDatabase("hr").employees;
    eventsCollection = session.getDatabase("reporting").events;

    session.startTransaction( { readConcern: { level: "snapshot" }, writeConcern: { w: "majority" } } );

    try{
        employeesCollection.updateOne( { employee: 3 }, { $set: { status: "Inactive" } } );
        eventsCollection.insertOne( { employee: 3, status: { new: "Inactive", old: "Active" } } );
    } catch (error) {
        print("Caught exception during transaction, aborting.");
        session.abortTransaction();
        throw error;
    }

    commitWithRetry(session);
}

// Start a session.启动会话。
session = db.getMongo().startSession( { readPreference: { mode: "primary" } } );

try{
   runTransactionWithRetry(updateEmployeeInfo, session);
} catch (error) {
   // Do something with error做一些错误的事情
} finally {
   session.endSession();
}