MongoDB - Support Oplog

Owned by Philippe Aquino
Jun 10, 2024
2 min read

Overview

Connect your MongoDB deployments to third-party tools by setting up oplog tailing so they can read events from the MongoDB oplog. The oplog (operations log) is a special capped collection that keeps a rolling record of all operations that modify the data stored in your database. This feature allows you to capture the operations that are to be replicated and is commonly used for integrating with third-party tools to read events from the MongoDB oplog. Additionally, oplog tailing is especially beneficial for Meteor apps, which rely on real-time data synchronization. By leveraging oplog tailing, your application server can be notified in real-time of any changes happening across your entire database, ensuring that your app reflects the most current state of the data.

This version highlights the usefulness of oplog tailing in integrating with third-party tools, as well as its specific benefits for Meteor apps in maintaining real-time data synchronization.

 

The oplog functionality in Galaxy Database is available exclusively for replicaset implementations. This ensures that operations can be replicated and integrated with third-party tools, providing real-time notifications for changes in your database, which is particularly beneficial for applications like Meteor.

Creating a MongoDB User for Oplog Tailing

Once your new MongoDB cluster is up and running, you can create a new user for oplog tailing by following these steps:

  1. Log in to the Galaxy Database Console.

  2. Go to your Galaxy Database page and click into your cluster.

  3. Connect to your cluster with the admin user

  4. Enter the following command into the cluster:

    use admin; db.createUser({user: "oploguser", pwd: "PasswordForOplog", roles: [{role: "read", db: "local"}]});

  5. Execute: Your MongoDB user for oplog tailing will now be created.

 

Connecting to the MongoDB Oplog

To connect to the oplog, ensure your connection string's authSource is set to the admin database you just created your oplog user on, but pointing to the local database where the oplog resides.

Using the following credentials for the new oplog user:

  • Username: oploguser

  • Password: PasswordForOplog

Your updated Connection String should look like this:

mongodb://oploguser:PasswordForOplog@galaxyhostingdb.meteor.com/local?authSource=admin&replicaSet=replicaSetName

You can find your MongoDB Connection String under the Overview tab of your MongoDB cluster details page in the Galaxy Database console.

This documentation should help users understand and effectively set up oplog tailing for their MongoDB databases using the Galaxy Database product. If more information or further clarification is needed, do not hesitate to consult the official documentation or contact technical support.