I jumped straight into the data model and workout logging flows, but probably should've spent more time clarifying scope first.
Start by clarifying the scope and core features of the fitness tracker, such as workout tracking, personalized plans, and social sharing. Then, outline a high-level architecture covering mobile clients, backend services, data storage, and third-party integrations, while discussing trade-offs in scalability, latency, and data consistency. Finally, dive into data modeling for workouts and user progress, and explain how you would handle real-time updates and offline support.
Pro tip: Emphasize how you would leverage Nike's existing ecosystem (e.g., Nike Run Club, Nike Training Club) and data to provide personalized recommendations, showing you understand the business context beyond just technical design.
Ask questions to understand the expected scale, key features (e.g., workout tracking, social features, personalized plans), and non-functional requirements like latency and availability. This ensures you design the right system.
Sketch the main components: mobile apps (iOS/Android), API gateway, backend services (user, workout, recommendation), databases, and external integrations (wearables, music). Discuss how they interact.
Design schemas for users, workouts, exercises, and progress. Choose appropriate databases (e.g., SQL for transactions, NoSQL for scalability, time-series for metrics) and explain trade-offs.
Address how to handle millions of users: caching, CDNs, sharding, read replicas, and asynchronous processing. Discuss trade-offs between consistency and availability.
Summarize key trade-offs made (e.g., SQL vs NoSQL, real-time vs batch). Mention potential extensions like offline mode, social features, or AI-driven personalization.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.