Vitess - Database clustering system for horizontal scaling of MySQL

Vitess is a database clustering system for horizontal scaling of MySQL through generalized sharding. By encapsulating shard-routing logic, Vitess allows application code and database queries to remain agnostic to the distribution of data onto multiple shards. With Vitess, you can even split and merge shards as your needs grow, with an atomic cutover step that takes only a few seconds.

Vitess has been a core component of YouTube's database infrastructure since 2011, and has grown to encompass tens of thousands of MySQL nodes.