Start by clarifying requirements and scale, then design the data model and core APIs for posts and follows. Focus on the feed generation strategy, comparing fan-out on write vs. read, and propose a hybrid approach with caching and ranking. Finally, discuss trade-offs, bottlenecks, and how to handle scale.
Pro tip: Show awareness of the read-heavy nature of the feed and the importance of precomputation and caching. Mention that you'd start with a simple solution and iterate, demonstrating pragmatism.
Ask questions to understand functional and non-functional requirements: number of users, read/write ratio, latency expectations, and features like ranking and media handling.
Define schemas for users, posts, follows, and feeds. Outline key APIs for creating posts, following users, and fetching the home feed.
Compare fan-out on write (push) vs. fan-out on read (pull) and propose a hybrid approach for scalability and freshness.
Select databases for different needs (e.g., graph for follows, wide-column for feeds) and design caching layers to reduce latency.
Highlight trade-offs (e.g., consistency vs. availability, latency vs. cost) and how to handle bottlenecks like hot users and media storage.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.