Start by clarifying requirements and scale, then propose a high-level architecture covering core features like user profiles, posts, and feeds. Dive into data modeling and trade-offs for scalability, consistency, and availability, focusing on feed generation and storage choices.
Pro tip: Emphasize the trade-offs between fan-out on write vs. read for feed generation, and discuss how to handle hot users and celebrity problem. Show awareness of cost and latency implications.
Ask questions to understand functional and non-functional requirements: scale (DAU, QPS), features (friends, posts, feed, messaging), consistency vs. availability, latency targets.
Sketch the main components: clients, API gateway, services (user, post, feed, graph), databases, caches, and message queues. Explain data flow for key operations like posting and viewing feed.
Design schemas for users, friendships (graph), posts, and feeds. Discuss SQL vs. NoSQL choices, sharding strategies, and indexing for efficient queries.
Compare fan-out on write vs. read, hybrid approach, and handling of celebrities. Discuss caching, ranking, and pagination.
Address scaling bottlenecks: database sharding, caching layers, CDN for media, and consistency models. Discuss trade-offs like latency vs. consistency, and cost.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.