How Discord Stores Trillions of Messages Without Breaking

Discord has over 500 million registered users, millions of active servers, and billions of messages sent every single day. But how do they actually store all of that data — without losing a single message, and without crashing? In this video, we break down the insane engineering behind Discord's database architecture: ▪️ Why Cassandra and Java's Garbage Collector became a massive problem at scale ▪️ How ScyllaDB and its Seastar framework eliminated lag spikes entirely ▪️ What a "Hot Partition" is — and why it nearly broke everything ▪️ How a custom Rust service solved it all with request coalescing This is the story of how Discord went from struggling with latency spikes to handling 4 trillion messages with millisecond response times. 🔔 Subscribe for more engineering breakdowns like this one. 💬 What tech should we break down next? Drop it in the comments.