In this blog post, we will explore how to use the Retryable Writes feature in Java MongoDB to ensure that write operations are retried in case of transient errors. Retryable Writes is a feature introduced in MongoDB 4.2 that allows write operations to be retried automatically if they fail due to network issues or other transient errors.

Table of Contents

• What are Retryable Writes?
• Enabling Retryable Writes in MongoDB
• Using Retryable Writes in Java MongoDB
• Example Code
• Conclusion
• References

What are Retryable Writes?

Retryable Writes is a feature in MongoDB that guarantees that write operations, such as inserts, updates, and deletes, are retried automatically in case of transient errors. Transient errors can occur due to network issues, temporary unavailability of resources, or other temporary failures.

With Retryable Writes, MongoDB ensures that write operations that fail due to transient errors are safely retried without requiring any manual intervention from the developer. This feature improves the reliability of write operations and simplifies error handling in applications.

Enabling Retryable Writes in MongoDB

To enable Retryable Writes in MongoDB, you need to have a replica set deployment running MongoDB 4.2 or later. Retryable Writes is not available in standalone deployments and requires a replica set.

Once you have a replica set, you can enable Retryable Writes by specifying the retryWrites connection string option as true when connecting to MongoDB using the MongoDB Java driver.

MongoClientSettings settings = MongoClientSettings.builder()
    .applyConnectionString(new ConnectionString("mongodb://localhost:27017"))
    .retryWrites(true)
    .build();
MongoClient mongoClient = MongoClients.create(settings);

By setting retryWrites to true, the MongoDB Java driver will automatically retry failed write operations.

Using Retryable Writes in Java MongoDB

Using Retryable Writes in Java MongoDB is quite straightforward. Once you have enabled Retryable Writes as described above, you can perform write operations as usual using the MongoDB Java driver.

The MongoDB Java driver will automatically retry failed write operations until they succeed, or until a non-transient error occurs. This allows your application to transparently handle transient errors without any additional code.

Example Code

Here’s an example code snippet that demonstrates how to use Retryable Writes in Java MongoDB:

MongoCollection<Document> collection = mongoClient.getDatabase("myDB").getCollection("myCollection");
Document document = new Document("key", "value");

try {
    collection.insertOne(document);
    System.out.println("Document inserted successfully.");
} catch (MongoException e) {
    System.out.println("Failed to insert document: " + e.getMessage());
}

In this example, the insertOne method is called to perform a write operation. If the operation fails due to a transient error, it will be automatically retried until it succeeds.

Conclusion

Retryable Writes is a valuable feature in MongoDB that ensures write operations are retried automatically in case of transient errors. By enabling Retryable Writes in your Java MongoDB application, you can significantly improve the reliability of write operations without the need for manual intervention.

Remember to always handle any potential non-transient errors that may occur during write operations, as Retryable Writes only handles transient errors.

So, go ahead and leverage the power of Retryable Writes in your Java MongoDB applications to enhance their reliability and resilience.

References

• MongoDB Documentation: Retryable Writes
• MongoDB Java Driver Documentation