AWS Certified Solutions Architect – Associate (SAA-C03)Design Resilient ArchitecturesMedium
A global e-commerce platform uses Amazon DynamoDB to store product catalogs and user shopping carts. The platform experiences unpredictable traffic spikes, with millions of requests per second during flash sales, followed by periods of low activity. The company needs to ensure consistent low-latency performance for all users globally, even during peak loads, without over-provisioning capacity. Which DynamoDB feature should be utilized?
- ADynamoDB Accelerator (DAX) with on-demand capacity.
- BProvisioned capacity mode with auto scaling.
- COn-demand capacity mode.
- DGlobal Tables with provisioned capacity.
Show answer & explanationAnswer & explanation
Correct answer: C. On-demand capacity mode.
DynamoDB's on-demand capacity mode automatically adjusts read and write throughput to accommodate unpredictable workloads without requiring capacity planning. This ensures consistent low-latency performance during sudden traffic spikes and periods of inactivity, and you only pay for the actual reads and writes, eliminating over-provisioning.
Why the other options are wrong
- A. DAX is an in-memory cache for microsecond response times, but it doesn't manage the underlying DynamoDB capacity scaling for unpredictable workloads. On-demand capacity is still needed for the base table.
- B. Provisioned capacity with auto scaling requires setting initial capacity and ranges, which can still lead to throttling if spikes are too sudden or over-provisioning if ranges are too high.
- D. Global Tables provide multi-region replication for global access and disaster recovery, but the capacity mode (provisioned or on-demand) is a separate consideration for handling variable loads.
DynamoDB On-Demand Capacity
A billing and capacity management mode for Amazon DynamoDB that automatically scales throughput to meet workload demand without requiring explicit capacity planning.
- Pay-per-request pricing for reads and writes.
- Ideal for unpredictable workloads with sudden spikes.
- No need to specify read/write capacity units (RCUs/WCUs).
Memory trick: On-demand is like a magic elastic band, stretching perfectly with every pull.