ProxySQL - High-performance MySQL proxy
ProxySQL is a high performance, high availability, protocol aware proxy for MySQL and forks (like Percona Server and MariaDB). It has an advanced multi-core architecture. It's built from the ground up to support hundreds of thousands of concurrent connections, multiplexed to potentially hundreds of backend servers. The largest ProxySQL deployment spans several hundred proxies.
ProxySQL’s configuration system is inspired from routers. You can dynamically configure everything, persist the configuration and modify it. All with 0 downtime. Its other feature include Query caching, Query Routing, Application layer proxy, Advanced topology support and lot more.
It also acts as a Firewall, In case of offending queries that cause problems to the DB (SQL injection or inefficient retrieval of information via SELECT * without WHERE, for example), ProxySQL acts as a gatekeeper between the application and the DB, allowing DBAs to react quickly.