At Box, the majority of our application data resides in a horizontally sharded MySQL infrastructure, made up of 100s of shards and 1000s of servers. We've built a distributed relational data service whose goal is to provide developers with a uniform, language-agnostic & performant way to interact with our application data at the scale of millions of requests per second. In this session, you will learn about some of the strategies that we employ in our distributed relational data service to protect our MySQL infrastructure. Strategies discussed will include rate limiting in a low-latency high-throughput environment and QoS enforcement to protect both our masters from load and replicas from lag.