Design a Feed Generation for Expedia
Last updated: December 14, 2025
Quick Overview
Design a scalable feed generation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Expedia
System Design
Software Engineer
Expedia
December 14, 2025Software Engineer
Onsite
System Design
Medium
50
11
338 solved
Design a scalable 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
Monitoring, logging, and alerting
Requirements gathering and capacity estimation
Database selection and data modeling
Consistency models and replication
Partitioning and sharding strategies
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 migrate from a monolithic to a microservices architecture?
- How would you handle a region-wide outage?
- How would you handle schema migrations with zero downtime?
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Requirements
Functional Requirements:
- Feed Generation: Generate personalized travel feeds for users based on their search history, preferences, and location.
- Real-time Updates: The system should ...
Capacity Estimation
Back-of-Envelope Calculations:
- User Base: Assuming 10 million active users on Expedia.
- Feed Requests: If each user requests their feed 5 times a day, this results in:
- Total requ...
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