Protect SLA and Choose Storage
DoorDashSoftware Engineer · Technical Screen
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This question evaluates system design competencies in service reliability and storage architecture, focusing on SLA protection during upstream latency spikes and trade-offs in choosing in-memory caches (e.g., Redis), relational databases, or alternative storage for order and payment state.
You own a service that calculates delivery-order payments from order lifecycle events.
Discuss two design questions:
- If an upstream dependency suddenly has very high latency, how would you keep your own service within its SLA?
- For storing order state and payment data, how would you choose between Redis, a relational database, or another storage system? Explain the trade-offs and your recommended architecture.
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