Design Data Pipeline Infrastructure for microservices
Last updated: July 1, 2025
Quick Overview
Design a event-driven data pipeline system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
PayPal
July 1, 2025291
10
871 solved
Design a event-driven data pipeline system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
ML system design at PayPal goes beyond model selection. This Onsite question evaluates your ability to design end-to-end ML pipelines, from data collection to model serving, while considering production constraints like latency and reliability.
What the Interviewer Expects
- Design the full ML lifecycle from data collection to model monitoring
- Address cold start, exploration/exploitation, and model freshness
- Discuss multi-objective optimization and ranking systems
- Plan for model debugging, fairness, and bias mitigation
- Design the feature store and training pipeline for scale
- Address model versioning, canary deployments, and rollback strategies
- Discuss the data flywheel and long-term system evolution
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 the cold start problem?
- How would you run A/B tests on different model versions?
- What is your model retraining strategy?
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Requirements
Functional Requirements
- Event Handling: The system must handle millions of events per second related to user transactions, including payments, refunds, and user behavior.
- **Data Processi...
Capacity Estimation
Assuming 10 million active users on PayPal, with each user generating an average of 10 events per day:
- Daily Events: 10 million users * 10 events = 100 million events/day.
- *Per Second Events...
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