Rene Cannao, ProxySQL author and CEO, discussed usage of ProxySQL for traffic control and scaling out at Percona Live Dublin 2017 on September 26, 2017.
Talk abstract is as follows:
The inability to control the traffic sent to MySQL is one of the worse nightmares for a DBA. Scaling out and high availability are only buzz words if the application doesn't support such architectures. ProxySQL is able to create an abstraction layer between the application and the database: controlling traffic at this layer hides the complexity of the database infrastructure from the application, allowing both HA and scale out. The same layer is able to protect the database infrastructure from abusive traffic, acting as a firewall and cache, and rewriting queries.