When to Replace DynamoDB With a Custom Key-Value Engine

DynamoDB is scalable and managed, but at very high throughput or strict latency, cost and behavior can push you toward a custom key-value engine.

• •Cost – You’re paying a lot for provisioned capacity or on-demand; the bill grows with traffic and doesn’t match your actual access pattern.
• •Latency – p99 or tail latency is too high for your use case (e.g. real-time, trading).
• •Access pattern – Your workload is mostly simple key-value; you don’t need DynamoDB’s global tables or secondary indexes, and you’d prefer to own the stack.

• •Lower cost at scale – Run on your own VMs or Kubernetes; no per-request or provisioned-capacity markup.
• •Predictable latency – Sub-ms p99 when designed for your schema and workload.
• •Full control – Persistence, replication, retention, and deployment tuned to your needs.

Usually: build the custom engine for the hot path, run it in parallel, migrate traffic gradually, then retire DynamoDB for that workload. Keep DynamoDB or another DB for other parts of the system if they fit. At Hendoi we build custom database engines (VeloxDB) for USA, Canada, and Bengaluru. Contact us for a free quote.