Design a geo-distributed Recommendation System
Last updated: April 3, 2026
Quick Overview
Design a geo-distributed recommendation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Plaid
April 3, 202622
13
3,002 solved
Design a geo-distributed recommendation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This is a common system design question asked during System Design Round at Plaid. 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. Plaid values engineers who can think about scalability from day one.
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
- What would the deployment pipeline look like for this system?
- How would you handle a region-wide outage?
- How would you implement rate limiting to protect the system?
- How do you ensure data consistency across multiple services?
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Requirements
Functional Requirements
- User Profile: The system must store user profiles, including preferences and interaction history.
- Recommendations: Generate personalized recommendations based...
Capacity Estimation
Assuming Plaid has around 10 million active users, with an average of 2 recommendations requested per user per day:
- Total Requests: 10 million users * 2 requests = 20 million requests per day. -...