Design a Video Streaming for PlanetScale
Last updated: June 13, 2026
Quick Overview
Design a scalable video streaming system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
PlanetScale
June 13, 20267
4
809 solved
Design a scalable video streaming system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This is a common system design question asked during Technical Screen at PlanetScale. The interviewer expects you to demonstrate your ability to design large-scale distributed systems, make well-reasoned trade-offs, and communicate your thought process clearly. PlanetScale values engineers who can think about scalability from day one.
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
- How would you optimize costs as the system scales?
- How would you implement rate limiting to protect the system?
- How would you handle a 10x increase in traffic overnight?
- How do you ensure data consistency across multiple services?
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Requirements
- Functional Requirements:
- Users must be able to upload videos in various formats (e.g., MP4, AVI).
- Users must be able to stream videos on demand with minimal buffering.
- The system sho...
Capacity Estimation
- Estimated Scale:
- Assume an average of 30 minutes watched per user per day.
- With 10 million concurrent users, that equates to 5 million hours of video streamed daily.
- If we assume an ...
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