Architect a low-latency Feed Generation Engine
Last updated: April 6, 2026
Quick Overview
Design a low-latency feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Citadel
April 6, 20267
9
4,251 solved
Design a low-latency feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Citadel asks this during the Technical Screen to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- What happens if one of your database nodes goes down?
- How would you optimize costs as the system scales?
- How would you handle a region-wide outage?
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Requirements
- Functional Requirements:
- Process millions of requests per second (QPS) for generating financial market feeds.
- Provide real-time updates with low latency (sub-100ms).
- Support various ...
Capacity Estimation
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Estimating QPS:
- Assume 1 million concurrent users, each generating 10 requests per second.
- Total QPS = 1,000,000 users * 10 requests/user = 10 million QPS.
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Storage Needs:
- Each...
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