Google Cloud SQL
App Engine provides a clear approach to running fully managed services in the cloud. Google created Cloud Datastore as a persistence solution with many of the same qualities – flexibility, scalability, and ease of use. While Datastore has proven to be a great product for many applications, it suffers from limited query support and an inability to model highly relational data. In October of 2011, Google released the developer preview of a fully managed MySQL database as a response to popular demand from App Engine developers.
"You can now choose to power your App Engine applications with a familiar relational database in a fully-managed cloud environment. This allows you to focus on developing your applications and services, free from the chores of managing, maintaining and administering relational databases."
Cloud SQL became available to the public in February of 2014. Two years later...