Design a event-driven Feed Generation System
Last updated: October 15, 2025
Quick Overview
Design a event-driven feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Scale AI
October 15, 202584
13
3,399 solved
Design a event-driven feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Scale AI typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Drive the design discussion proactively with minimal interviewer guidance
- Perform detailed capacity estimation and use it to inform design decisions
- Design for global scale with multi-region deployment and data consistency
- Deep dive into 2-3 critical components with implementation-level detail
- Address complex trade-offs: CAP theorem, eventual consistency, conflict resolution
- Discuss operational excellence: deployment strategy, chaos engineering, SLOs/SLIs
- Propose a phased rollout plan from MVP to full-scale system
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 handle a region-wide outage?
- What would the deployment pipeline look like for this system?
- How would you handle schema migrations with zero downtime?
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Requirements
- Functional Requirements:
- Ability to generate feeds in real-time based on incoming events from multiple sources.
- Support for filtering, sorting, and ranking of events for personalized f...
Capacity Estimation
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Assumptions:
- Each user generates an average of 100 events per day.
- Scale AI aims to support 1 million active users.
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Calculations:
- Daily events = 1,000,000 users * 100 event...
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