Design a large-scale Notification Platform
Last updated: April 9, 2026
Quick Overview
Design a real-time notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
SpaceX
System Design
Software Engineer
SpaceX
April 9, 2026Software Engineer
Onsite
System Design
Easy
342
14
1,965 solved
Design a real-time notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
ML system design at SpaceX 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
- Map the business problem to a concrete ML objective
- Propose reasonable features and a baseline model
- Discuss basic model evaluation metrics
- Outline a simple serving architecture
Key Topics to Cover
Monitoring and model degradation detection
Feature engineering and feature stores
Model selection and architecture
A/B testing and experimentation
Training pipeline and infrastructure
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 run A/B tests on different model versions?
- How would you handle the cold start problem?
- How would you debug a model that works well offline but poorly online?
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Requirements
Functional Requirements
- Real-time Notifications: Users should receive notifications in real-time about launches, updates, and operational alerts.
- User Preferences: Allow users to cus...
Capacity Estimation
Assuming SpaceX has approximately 10 million users:
- Peak Notification Events: During a rocket launch, assume 10% of users (1 million) opt to receive notifications.
- Notification Frequency: ...
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