6 / 6 Fan-Out on Write vs Read

The New Follow

In a push-based feed, a user follows a new account and then sees nothing from it until that account publishes again, which may be days later. What is the correct explanation and remedy?

A

The timeline is capped at a fixed number of entries, so the new author's posts were evicted by the higher-volume accounts the user already follows

B

Fan-out only populates timelines on publish, so following must trigger a backfill of the author's recent posts into the follower's timeline or a read-time union for recent follows

C

The follow edge is cached on the feed service, so invalidating that cache entry forces the timeline to be recomputed with the new author's recent posts included

D

The follow write has not yet propagated to the fan-out workers, and the feed converges on its own within the eventual-consistency window once those workers pick up the new follow edge