ProxySQL is a MySQL protocol aware, reverse proxy for database servers using the MySQL protocol, ranging from standalone MySQL/MariaDB/Percona, to clustering solution like Galera/PXC and Group Replication, to cloud platforms like RDS and Aurora. It is designed to handle millions of distinct users, millions of connections, and thousands of servers. In this session we will cover the internals that allow to efficiently handle traffic of large scale-out MySQL deployments. Specifically we will cover: - threading model and connections handling - non-blocking, async network I/O - state machine related to session tracking and management - traffic routing - backends monitoring