Hybrid fan-out.

also: hybrid feed · celebrity problem · hybrid push/pull · hybrid push-pull

Push 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.

also: hybrid feed · celebrity problem · hybrid push/pull · hybrid push-pull

Push posts from regular users into feeds on write; pull celebrities' posts at read time and merge them in.

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.