Cassandra and DynamoDB are both distributed NoSQL databases, but they have key differences in architecture, scalability, and use cases. Here's a detailed comparison:
1. Architecture
Feature
Cassandra
DynamoDB
Model
Open-source, decentralized, peer-to-peer
Managed, serverless, centralized with regional replication
Consistency
Tunable consistency (can be strong or eventual)
Strong or eventual consistency per request
Replication
Multi-datacenter replication supported
AWS-native cross-region replication
Partitioning
Consistent hashing with virtual nodes (vnodes)
Partitioned by AWS internal mechanisms
2. Scalability & Performance
Feature
Cassandra
DynamoDB
Scaling
Scales horizontally by adding nodes
Fully managed auto-scaling
Read/Write Performance
High throughput with tunable read/write consistency
Predictable latency with automatic scaling
Storage Model
Append-only log-structured storage
SSD-backed, automatically optimized
Hot Partitions
Can suffer from hot partitions if data is not well distributed
Can have throttling issues on partitions due to AWS limits
3. Data Model & Querying
Feature
Cassandra
DynamoDB
Data Model
Wide-column store
Key-value and document store
Query Language
CQL (SQL-like)
NoSQL API (AWS SDK or PartiQL)
Indexes
Supports secondary indexes but can be inefficient
Global secondary indexes (GSIs) and local secondary indexes (LSIs)
Joins & Aggregations
No native support, needs application-level joins
Limited aggregation with DynamoDB Streams or AWS Lambda
4. Availability & Durability
Feature
Cassandra
DynamoDB
High Availability
Highly available due to decentralized architecture