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
System Design
Software Engineer
Scale AI
October 15, 2025
Software Engineer
System Design Round
System Design
Hard

84

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
Database selection and data modeling
Consistency models and replication
Security and authentication
Partitioning and sharding strategies
Message queues and async processing
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. 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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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For event-driven Feed Generation System, key functional requirements incl...

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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