Design A/B Testing Infrastructure for real-time analytics
Last updated: September 9, 2025
Quick Overview
Design a low-latency a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Adobe
September 9, 20258
10
2,778 solved
Design a low-latency a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Adobe asks this during the System Design Round 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
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
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 implement rate limiting to protect the system?
- How do you ensure data consistency across multiple services?
- How would you migrate from a monolithic to a microservices architecture?
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Requirements
Functional Requirements
- Experiment Creation: Allow users to create A/B tests by defining variants, targeting criteria, and duration.
- Real-time Analytics: Provide dashboards to displa...
Capacity Estimation
Assuming Adobe has 100 million active users, and we expect 10% of them to interact with A/B tests daily. This leads to:
- Daily requests = 10 million
- If each test lasts for 7 days, we could have aro...
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