Inside Facebook's News Feed Architecture
Chapter 1: The Scale & SLA Challenge"Every single day, more than three billion people around the globe unlock their phones and launch Facebook. Within a split second, a personalized feed appears on their screen—populated with photos from close friends, trending videos, group discussions, and targeted announcements. To the average user, this feels like magic. But beneath this clean mobile interface lies one of the most sophisticated and terrifyingly complex distributed systems ever engineered by humankind.Consider the sheer operational scale. At any given moment, there are tens of thousands of candidate posts competing for space on your screen. If Facebook used a naive SQL database query to search through billions of posts across millions of friends, the network would freeze immediately. Yet, the engineering requirement—the strictly enforced Service Level Agreement—mandates that your news feed must render in less than three hundred milliseconds with high availability. How do you filter, rank, and assemble a totally unique content stream for billions of concurrent users in the blink of an eye? Let’s step behind the curtain and dissect the architecture."
