Introduction
One of the things I like about Continuent Tungsten is how Tungsten Connector can hold traffic while a (graceful) master switch is taking place. This means the application may experience a brief spike in latency, but has not returned any errors from the database layer.
René also described a similar process using ProxySQL and mysqlrpladmin here. In this post we will try to achieve the same feat, a graceful master switchover with ProxySQL and Orchestrator.
ProxySQL considerations
ProxySQL needs to isolate our application from the changes going
on at the database layer.
By design, if a query needs to be sent to a hostgroup that has no
servers in ONLINE state, ProxySQL waits until either a server
becomes available or a timeout expires
(mysql-connect_timeout_server_max if I am not …