MariaDB supports online alter for many types of changes; however, some alters still require a table copy, and an online schema change tool is desired. The GitHub online schema change transmogrifer, gh-ost, is a new tool that I have already had the pleasure of using in production environments successfully. I will present a use case for running the tool in a complex multi-source, multi-slave replication topology to make changes unsupported by the native MariaDB online alter. This presentation will include a demonstration of the operational tools within gh-ost to throttle or view the status of the running alter process.
Getting It Right: Online Schema Migration with gh-ost