Amazon DocumentDB is fully managed document database service that supports MongoDB workloads at scale. As a document database, Amazon DocumentDB makes it easy to store, query, and index JSON data.


Key Points 

  • Amazon DocumentDB is a fully managed service that is compatible with MongoDB.
    • Amazon DocumentDB supports various applications, drivers and tools that work with MongoDB.
    • Amazon DocumentDB enables the compatibility by virtue of implementing MongoDB API on top of Amazon DocumentDB implementation.
  • Amazon DocumentDB is highly available – replicates 6 copies of data across three AZs.
  • Like many other Amazon databases, Amazon DocumentDB decouples underlying compute and storage, allowing each to scale independently.
  • Amazon DocumentDB supports read capacity up to millions of requests per second by leveraging up to 15 Read Replicas.
  • You can use AWS Data Migration Service (DMS) to migrate MongoDB databases to Amazon DocumentDB.
    • AWS provides DMS free for six months to transfer your MongoDB data to DocumentDB.
  • Encryption – data is encrypted at rest, and in transit.


Components of Amazon DocumentDB


Following diagram shows simplified architecture of DocumentDB:

Simplified architecture of DocumentDB

Image courtesy of AWS


Read Replicas

DocumentDB supports Read Replicas, with following characteristics:

  • Replicas share the same underlying storage volumes as the primary instance
  • You can have up to 15 Read Replicas
  • Replication is done asynchronously (typically with milliseconds lag)
  • DocumentDB can automatically failover to one of the Replicas
    • You can assign priorities to Replica instances
  • Replicas stay within the Region – that is – no cross-Region replicas allowed

Backup and Restore

Automatic Backups

  • DocumentDB supports automatic backups, and Point-in-time Restore.
  • You can enable backup window for point-in-time restore up to 35 days.

Manual Backups

  • You can take manual snapshots of DocumentDB clusters.
  • These snapshots are retained until you manually delete them.
  • Restoring from manual snapshots require creation of new Clusters



DocumentDB billing is done on following components:

  1. On-demand instances – per second (with 10-minute minimum)
  2. Database I/O – per million I/Os for read or writes
  3. Database Storage – per GB per month
  4. Backup Storage – per GB per month


Following diagram provides a simplified conceptual view of DocumentDB architecture and above components are billed:

Simplified conceptual view of DocumentDB

Image courtesy of AWS


External Resources