Scalability

When Amazon engineers published the Dynamo paper in 2007, they revealed a technique that had been quietly powering some of the world’s largest distributed systems. The core idea—consistent hashing—originated from a 1997 MIT paper by David Karger and colleagues, but it took a decade before the industry fully embraced its elegance. Today, consistent hashing underpins Apache Cassandra, Amazon DynamoDB, Discord’s messaging infrastructure, Netflix’s content delivery network, and virtually every modern distributed database. The algorithm solves a deceptively simple problem: how do you distribute data across servers when those servers keep joining and leaving? ...

The Oracle Real-World Performance group published a demonstration that should have changed how every developer thinks about connection pools. They took a system struggling with ~100ms average response times and reduced those times to ~2ms—a 50x improvement. They didn’t add hardware. They didn’t rewrite queries. They reduced the connection pool size from 2048 connections down to 96. Most developers configure connection pools based on intuition: more users means more connections, right? A typical production configuration sets the pool to 100, 200, or even 500 connections “just to be safe.” This intuition is precisely backwards. The correct question isn’t how to make your pool bigger—it’s how small you can make it while still handling your load. ...