Hybrid fan-out.
also: hybrid feed · celebrity problem · hybrid push/pull · hybrid push-pullPush posts from regular users into feeds on write; pull celebrities' posts at read time and merge them in.
the two-minute refresher
- A celebrity with 300M followers would mean 300M feed writes per post: nearly an hour of fan-out.
- Split by follower count (say 10,000): below it push, above it pull.
- Reads merge the precomputed feed with a few celebrities' recent posts.
- How large social networks run feeds in practice.