Architect a event-driven Recommendation Engine
Last updated: June 14, 2026
Quick Overview
Design a event-driven recommendation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Morgan Stanley
System Design
Software Engineer
Morgan Stanley
June 14, 2026Software Engineer
System Design Round
System Design
Medium
1
8
269 solved
Design a event-driven recommendation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Morgan Stanley asks this during the System Design Round 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
Database selection and data modeling
Message queues and async processing
High-level architecture and component design
Monitoring, logging, and alerting
Partitioning and sharding strategies
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 monitoring and alerting would you set up on day one?
- What happens if one of your database nodes goes down?
- How would you migrate from a monolithic to a microservices architecture?
Practice a Similar Problem on Codemia
Solve a related problem with our interactive workspace, get AI feedback, and view detailed solutions.
Solve on CodemiaSample Answer
Requirements
Functional Requirements:
- Real-time Recommendations: The system should provide personalized recommendations to users based on their interactions and preferences.
- Event Processing: The...
Capacity Estimation
Back-of-Envelope Calculations:
- User Base: Assume 10 million active users.
- Requests Per Second (QPS): If each user generates 6 requests per hour on average, that translates to:
- 10,0...
Submit Your Answer
Markdown supported