Design a event-driven Feed Generation System
Last updated: May 7, 2026
Quick Overview
Design a event-driven feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Expedia
May 7, 2026134
9
753 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 Expedia 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
- 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
- What happens if one of your database nodes goes down?
- What would the deployment pipeline look like for this system?
- How would you handle a 10x increase in traffic overnight?
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Requirements
Functional Requirements:
- Event Processing: The system should be able to process event streams from various sources (e.g., booking events, user actions) in real-time.
- Feed Generation:...
Capacity Estimation
Assuming Expedia processes approximately 10 million events per day:
- Requests Per Second (QPS): 10,000,000 events / 86400 seconds = ~115.74 QPS.
- Storage Requirements: If each event averages...
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