Compare PostgreSQL and DynamoDB for application databases. Understand relational consistency vs NoSQL scalability, and when to choose each for your workload.
| Aspect | PostgreSQL | DynamoDB | Winner |
|---|---|---|---|
| Data model | Relational tables with schemas | Key-value and document | Draw |
| Query flexibility | Unlimited — any SQL query possible | Limited to primary key and index lookups | PostgreSQL |
| Scaling | Vertical scaling or read replicas | Horizontal — virtually unlimited throughput | DynamoDB |
| Operations | Self-hosted or managed (RDS) | Fully managed serverless | DynamoDB |
| Consistency | Strong consistency by default | Eventual consistency (strong available) | PostgreSQL |
For simple key-value lookups at scale, yes. DynamoDB delivers consistent single-digit millisecond latency. For complex queries with JOINs and aggregations, PostgreSQL is faster and more flexible.
PostgreSQL (self-hosted) has predictable costs based on hardware. DynamoDB has pay-per-request pricing that scales to zero but can become expensive at high throughput. Compare your specific workload patterns.