The linked https://www.percona.com/doc/percona-toolkit/2.1/pt-online-schema-change.html https://www.percona.com/doc/percona-toolkit/2.1/pt-online-sc... generall

The linked https://www.percona.com/doc/percona-toolkit/2.1/pt-online-schema-change.html https://www.percona.com/doc/percona-toolkit/2.1/pt-online-sc... generally works really well though, and in the simplest case it's as easy as following the usage example. I'm surprised that they knew about it yet didn't invest the time to learn it.