This document discusses two high availability solutions for MySQL: InnoDB Cluster and NDB Cluster. InnoDB Cluster provides high availability using MySQL 5.7+ features like Group Replication and allows for read scalability and application failover using MySQL Router. NDB Cluster uses an in-memory database with automatic sharding and native high availability features in the NDB storage engine. The document compares the two solutions and outlines some of their key differences like consistency models, sharding capabilities, and operational complexity.