Learn all about MongoDB Incremental Backups from our experts. Our MongoDB Support team is here to help you with your questions and concerns.

What are MongoDB Incremental Backup

The process of taking incremental backup involves taking backups of only the latest changes or updates made to the database since the last full backup. This comes in handy in saving time as well as storage space since the entire database is not duplicated during each backup.

We can perform an incremental backup in MongoDB with a tool mongodump. This tool relies on a combination of oplog as well as snapshots to record the changes made to the database.

Oplog are MongoDB operation logs. It is a type of special MongoDB collection that keeps track of all write operations performed on the database. The state of the database at any given time can be recreated easily by replaying these processes.

On the other hand, Snapshots are point-in-time representations of the database. They are stored in a separate file or disk. Furthermore, they are taken periodically to save the database state at a specific point in time.

The mongodump tool uses the latest full backup and the oplog to identify the changes made to the database. After that, it takes a snapshot of the changed data and saves it as a backup file. Additionally, we can automate the process using periodically scheduled scripts.

How to take MongoDB Incremental Backup

1. Before we start taking incremental backups, we have to first take a full incremental backup. In other words, we need to take a complete backup as seen below that will serve as the base for upcoming incremental backups.

   pbm backup -type incremental –base

   The above command pushes the pbm-agent starts to track the incremental backup history in order to calculate and save the changes in data blocks.
2. Next, we can run regular incremental backups with this command:

   pbm backup -type incremental

As mentioned earlier we can schedule scrips to run this command periodically to take incremental backups at regular intervals.

How to restore data from a MongoDB Incremental Backup

We can easily restore data from an incremental backup with the following command:

pbm restore 2023-03-34NT62:24:51X

Remember to replace 2023-03-34NT62:24:51X with the corresponding backup name.

When we run the above command, Percona Backup for MongoDB locates the base incremental backup and then restores the data from it. After that, it restores the modified data from the corresponding incremental backups.

Once the restore is complete, we have to restart all mongod nodes and pbm-agents. Additionally, we have to resync the backup list from the storage. Our experts also recommend taking a new base backup in order to renew the starting point for upcoming incremental backups.

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Conclusion

To sum up, our Support Techs introduced us to MongoDB Incremental Backups and also demonstrated how to take an incremental backup with ease.