Transactions

Overview

In this guide, you can learn how to use transactions with the MongoDB Go Driver. Transactions allow you to run a series of operations that do not change any data until the transaction is committed. If any operation in the transaction fails, the driver aborts the transaction and discards all data changes before they ever become visible.

In MongoDB, transactions run within logical sessions. A session is a grouping of related read or write operations that you intend to run sequentially. Sessions enable causal consistency for a group of operations or allow you to execute operations in an ACID transaction. MongoDB guarantees that the data involved in your transaction operations remains consistent, even if the operations encounter unexpected errors.

With the Go driver, you can create a new session from a Client instance as a Session type. We recommend that you reuse your client for multiple sessions and transactions instead of instantiating a new client each time.

Methods

After you start a session using the StartSession() method, you can modify the session state using the method set provided by the Session interface. The following table describes these methods:

The Session interface also has methods to retrieve session properties and modify mutable session properties. Find more information in the API documentation.

Example

The following example shows how you can create a session, create a transaction, and commit a multi-document insert operation through the following steps:

1. Create a session from the client using the StartSession() method.

2. Use the WithTransaction() method to start a transaction.

3. Insert multiple documents. The WithTransaction() method executes the insert and commits the transaction. If any operation results in errors, WithTransaction() handles aborting the transaction.

4. Close the transaction and session using the EndSession() method.

wc := writeconcern.New(writeconcern.WMajority())
txnOptions := options.Transaction().SetWriteConcern(wc)
session, err := client.StartSession()
if err != nil {
	panic(err)
}
defer session.EndSession(context.TODO())
result, err := session.WithTransaction(context.TODO(), func(ctx mongo.SessionContext) (interface{}, error) {
	result, err := coll.InsertMany(ctx, []interface{}{
		bson.D{{"title", "The Bluest Eye"}, {"author", "Toni Morrison"}},
		bson.D{{"title", "Sula"}, {"author", "Toni Morrison"}},
		bson.D{{"title", "Song of Solomon"}, {"author", "Toni Morrison"}},
	})
	return result, err
}, txnOptions)

If you need more control over your transactions, you can find an example showing how to manually create, commit, and abort transactions in the full code example.

Additional Information

For more information about insert operations, see the Insert a Document fundamentals page.

For more information about write concerns, see the Modify Execution of CRUD Operations fundamentals page.

For an additional example using sessions and transactions with the Go driver, see the developer blog post on Multi-Document ACID Transactions.