Design Feed Generation Infrastructure for mobile apps
Last updated: December 25, 2025
Quick Overview
Design a fault-tolerant feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Google
System Design
Software Engineer
Software Engineer
Onsite
System Design
Medium
2
14
612 solved
Design a fault-tolerant feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Google asks this during the Onsite 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
Consistency models and replication
High-level architecture and component design
Monitoring, logging, and alerting
Requirements gathering and capacity estimation
Message queues and async processing
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 do you ensure data consistency across multiple services?
- How would you handle schema migrations with zero downtime?
- How would you handle a region-wide outage?
- 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:
- Feed Generation: The system must generate personalized feeds for mobile app users based on their preferences and interactions.
- Real-time Updates: Users shoul...
Capacity Estimation
Back-of-Envelope Calculations:
- User Base: Assume 100 million active users.
- Requests per User: Each user requests their feed every 5 minutes.
- Total Requests per Minute (RPM): 100M...
Submit Your Answer
Markdown supported