How do you back up and restore a document database?

Backing up and restoring a document database involves using built-in tools, cloud services, or custom scripts to capture data and metadata, then reapplying it when needed. The exact steps depend on the database system (e.g., MongoDB, Couchbase) and hosting environment, but the core principles remain consistent: create reliable copies of data, store them securely, and validate recovery processes.

For backups, most document databases offer native utilities. MongoDB, for example, provides mongodump to export data as BSON files, which can be stored locally or in cloud storage like AWS S3. Cloud-managed services like AWS DocumentDB or Azure Cosmos DB automate backups using snapshots, capturing the database’s state at specific intervals. Incremental backups (tracking changes since the last backup) reduce storage costs and time, while full backups ensure complete recovery points. It’s critical to encrypt backups and store them in geographically separate locations to guard against data center failures. For instance, Firebase Firestore users can schedule exports to Google Cloud Storage and enable object versioning to prevent accidental deletion.

Restoring requires reversing the backup process. MongoDB’s mongorestore imports BSON backups into a new or existing database, but you must ensure indexes and user permissions are reapplied. Cloud services often let you restore snapshots to a new instance with a few clicks, though you may need to adjust connection strings in your application. Always test restores in a staging environment to verify data consistency and performance—common pitfalls include missing indexes, incomplete transaction logs, or version mismatches. For example, restoring a sharded MongoDB cluster requires ensuring all shards and config servers are synchronized to avoid data fragmentation.

Key considerations include automating backups (e.g., cron jobs or cloud scheduler), monitoring backup success, and documenting recovery steps. Avoid downtime during backups by using tools that support hot backups (like Couchbase’s cbbackupmgr) or leveraging point-in-time recovery features. Regularly audit backup retention policies to comply with data regulations. By combining system-specific tools, cloud services, and thorough testing, developers can ensure reliable recovery from data loss or corruption.