Design a News Feed
Design the backend for a social news feed: following, posting, and a personalized timeline. Compare fan-out-on-write and fan-out-on-read, explain how you would handle accounts with millions of followers, and sketch where a ranking service fits in the read path.
Hints
Hint 1
Precomputing timelines is cheap for most users and ruinous for celebrities — hybrid fan-out exists for a reason.
Hint 2
Separate the storage problem (what happened) from the ranking problem (what to show first).
Asked at
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