1 / 6 Fan-Out on Write vs Read

Best Of Both Inboxes

A team adopts a hybrid fan-out design after both pure models failed at scale. What does the hybrid actually do?

A

Fan-out writes are queued during peak hours and applied to follower timelines overnight, so the same total work is spread evenly across the day

B

Posts from ordinary accounts are pushed into follower timelines, posts from a small set of very-high-follower accounts are pulled at read time, and the two are merged per request

C

Posts from very-high-follower accounts are pushed into follower timelines because those posts matter most, and everything from ordinary accounts is pulled and merged at read time

D

Every post is written to both a materialized timeline and a pull index, and the feed serves whichever of the two sources responds first on a given request