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.
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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
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?
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Requirements Clarification
Before diving into the architecture, clarify the scope with the interviewer. For Feed Generation Infrastructure for mobile apps, key functional requir...
Capacity Estimation
Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...
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