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Azure Cosmos DB vs Azure DocumentDB

Azure Cosmos DB: Microsoft's globally distributed, multi-API NoSQL and vector database with SLA-backed latency. Azure DocumentDB: Microsoft's managed MongoDB-compatible service, built on the open-source DocumentDB engine.

key differences

  • Azure Cosmos DB is built for larger datasets (Multi-PB) than Azure DocumentDB (≤ 1 PB).
  • Transactions: Azure Cosmos DB offers limited ACID; Azure DocumentDB offers full.
  • Only Azure Cosmos DB has change data capture, triggers, stored procedures, columnar storage.
  • Only Azure DocumentDB has joins.
  • Azure Cosmos DB has a serverless option; Azure DocumentDB does not.

choose azure-cosmos-db for

  • +Globally distributed user and session data
  • +IoT telemetry and device state
  • +Chat history and memory for AI agents
  • +Retail carts, catalogs and personalization

best at · OLTP, IoT, Sessions

choose azure-documentdb for

  • +MongoDB migrations to Azure without SSPL
  • +Content management and catalog backends with complex aggregations
  • +RAG applications storing embeddings next to documents

best at · OLTP, Content, Vector search

Azure Cosmos DBMicrosoft's globally distributed, multi-API NoSQL and vector database with SLA-backed latency.
Azure DocumentDBMicrosoft's managed MongoDB-compatible service, built on the open-source DocumentDB engine.
overview
Primary model
Document
Document
Also supports
Key-Value, Graph, Wide-Column, Vector, Search Engine
Vector, Spatial
Type
Managed service
Managed service
Status
Active
Active
Developer
Microsoft
Microsoft
First release
2017
2023
Latest version
–
–
License
ProprietaryProprietary Azure service
ProprietaryProprietary Azure service (engine is MIT-licensed DocumentDB)
Free tier
✓
✓
popularity
WhichDB Score
45.3
0.0
Rank
#39
#692
GitHub stars
–
–
Stack Overflow questions
7.8K
–
scale & guarantees
Comfortable data size
Massive (Multi-PB)
Large (≤ 1 PB)
Horizontal scaling
Native
Native
Multi-region
Active active
Read replicas
ACID
Limited
Full
Consistency
Tunable, Strong, Causal, Eventual
Strong
Schema
Schemaless
Schemaless
Architecture
Distributed, Multi primary, Serverless
Distributed, Primary replica
deployment
Self-hosted
—
—
Vendor-managed cloud
✓
✓
Serverless
✓
—
Embedded
—
—
Edge
—
—
Clouds
Azure
Azure
capabilities
Transactions
✓
✓
Joins
—
✓
Secondary indexes
✓
✓
Full-text search
✓
✓
Vector search
✓
✓
Geospatial
✓
✓
JSON
✓
✓
Change data capture
✓
—
Triggers
✓
—
Stored procedures
✓
—
Materialized views
—
—
TTL / expiry
✓
✓
Pub/Sub
—
—
Columnar storage
✓
—
In-memory
—
—
Durable persistence
✓
✓
Compression
—
—
Encryption at rest
✓
✓
Role-based access
✓
✓
Time travel
—
—
Branching
—
—
Online schema changes
✓
✓
Streaming ingest
—
—
Offline sync
—
—
Runs in WebAssembly
—
—
interfaces
Query languages
Cosmos DB NoSQL (SQL dialect), MongoDB Query API, CQL, Gremlin
MongoDB Query API (MQL), Aggregation pipeline
Client languages
C#, Java, JavaScript, Python, Go, Rust
C#, Java, Python, JavaScript, Go
Best for
OLTP, IoT, Sessions, Vector search
OLTP, Content, Vector search, RAG
Add more to this comparisonNot sure either fits? Try smart match

Azure Cosmos DB vs Azure DocumentDB: FAQ

What is the difference between Azure Cosmos DB and Azure DocumentDB?

Azure Cosmos DB: Microsoft's globally distributed, multi-API NoSQL and vector database with SLA-backed latency. Azure DocumentDB: Microsoft's managed MongoDB-compatible service, built on the open-source DocumentDB engine. Azure Cosmos DB is built for larger datasets (Multi-PB) than Azure DocumentDB (≤ 1 PB). Transactions: Azure Cosmos DB offers limited ACID; Azure DocumentDB offers full. Only Azure Cosmos DB has change data capture, triggers, stored procedures, columnar storage.

When should I choose Azure Cosmos DB over Azure DocumentDB?

Choose Azure Cosmos DB for globally distributed user and session data; IoT telemetry and device state; and chat history and memory for AI agents. Choose Azure DocumentDB for MongoDB migrations to Azure without SSPL; content management and catalog backends with complex aggregations; and RAG applications storing embeddings next to documents.

Is Azure Cosmos DB or Azure DocumentDB more popular?

Azure Cosmos DB ranks #39 on the WhichDB Score (45.3/100) and Azure DocumentDB ranks #692 (0.0/100). Popularity is not fit: check the requirements that matter for your project.

Are Azure Cosmos DB and Azure DocumentDB open source?

No. Azure Cosmos DB is proprietary, closed-source software. No. Azure DocumentDB is proprietary, closed-source software.