The distributed database behind Twitter is a complex system that has evolved over time to meet the company's growing needs for scalability and reliability. The system started with a monolithic architecture based on MySQL, but as Twitter's popularity grew, engineers sought to improve performance by migrating to microservices, multiple datacenters, and eventually building their own custom in-house distributed database solution called Manhattan. Today, Manhattan is a massive system that powers tens of thousands of nodes, serves many petabytes of data, and handles tens of millions of requests per second. Despite its complexity, the Twitter engineering team continues to evolve and refine the system, incorporating new technologies such as Kubernetes, Kafka, and public cloud storage. The diversity of use cases in a company of Twitter's size means that no single database can meet all their needs, leading the team to explore alternative solutions that may complement or even replace internal offerings.