Nice article on how to enable GTID without shutting down MySQL. There is no officially supported way to enable the GTID bit in MySQL without shutting down the server, so thanks for the step-by-step instructions on how to change to GTID without compromising on high availability. This seems to be what Facebook does on their production systems also. Given that Booking and Facebook both do this, it is likely scalable. Have you considered submitting a pull request to the MySQL codebase to have a flag that enables this?