Resolving the Clock: A Practical Look at Timeline Architecture Choices
Timeline architectures are the invisible engines behind social media feeds, project management boards, event logs, and notification streams. When they work well, users see fresh content instantly; when they fail, queries time out, data goes stale, and engineering teams scramble to patch workarounds. This guide offers a practical, conceptual look at the three dominant timeline architecture choices — pull-based, push-based, and hybrid models — and helps you decide which one fits your specific constraints. Why Timeline Architecture Matters: The Core Problem Every timeline system faces a fundamental tension: how to balance write cost against read cost. In a social feed, for example, a single user may follow thousands of accounts, each publishing multiple times per day. Reading that combined feed in real time requires either pre-computing the merged view (fan-out on write) or computing it on demand (fan-out on read).