Design a high-throughput Video Streaming System
Last updated: November 19, 2025
Quick Overview
Design a high-throughput video streaming system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Citadel
November 19, 202542
5
2,340 solved
Design a high-throughput video streaming system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This fundamentals question from Citadel's Technical Screen tests whether you can reason about software design at a deep level. The interviewer expects discussion of maintainability, testability, and operational considerations.
What the Interviewer Expects
- Design a complex system component applying multiple engineering principles
- Reason about system-level trade-offs: performance, reliability, developer experience
- Discuss advanced patterns: event sourcing, CQRS, distributed transactions
- Address cross-cutting concerns: observability, security, backward compatibility
- Demonstrate depth in both theoretical foundations and practical implementation
Key Topics to Cover
How to Approach This
- Apply SOLID principles. Single Responsibility makes code testable, Open/Closed makes it extensible.
- Choose data structures based on access patterns, not familiarity.
- Prefer immutable data and message passing over shared mutable state for concurrency.
- Design APIs with RESTful conventions, versioning, meaningful errors, and pagination from day one.
Possible Follow-up Questions
- How would this design change if the team size doubled?
- How would you measure the performance of this component in production?
- How would you handle backward compatibility?
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Core Design Principles
For a high-throughput video streaming system at Citadel, the CAP theorem is paramount. We must balance Consistency, Availability, and Partition Tolerance. With millions of concurrent u...
Architecture
The architecture is based on a Microservices pattern using a CQRS (Command Query Responsibility Segregation) approach. This allows us to separate the read and write operations of our system, o...
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