Design Recommendation Infrastructure for microservices
Last updated: January 9, 2026
Quick Overview
Design a high-throughput recommendation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Discord
January 9, 202641
11
4,911 solved
Design a high-throughput recommendation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Discord 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
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
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 implement rate limiting to protect the system?
- How do you ensure data consistency across multiple services?
- How would you migrate from a monolithic to a microservices architecture?
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Requirements
Functional Requirements:
- Recommendation Generation: The system should generate real-time recommendations for users based on their activity, preferences, and interactions within Discord.
- ...
Capacity Estimation
To estimate capacity, we consider the following assumptions:
- Active Users: 100 million monthly active users on Discord.
- Daily Active Users: Approximately 20% (20 million users) engage dail...
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