When I joined the Percona Support team in early 2013, MySQL 5.6 was being launched. I remember all the buzz and euphoria surrounding its release: it was a big step from the 5.5 series, carrying important changes in the MySQL architecture and internals that brought highly anticipated features such as the (still incipient) multi-threaded replication [&]

https://www.percona.com/blog/2021/06/01/inspecting-mysql-servers-part-1-the-percona-support-way/