The document discusses X DevAPI, which allows MySQL to be used as both a relational and non-relational (schema-less) database. It provides NoSQL and SQL functionality in a single database using CRUD operations. The presenter worked with X DevAPI at Wix, where they initially used ProxySQL for failover but it did not support X DevAPI. They were able to use InnoDB cluster instead to gain its automatic failover capabilities while taking advantage of X DevAPI.