As many of you may remember, Percona added the super_read_only feature way back in Percona Server for MySQL 5.6.21, based on work done by WebScaleSQL. This feature eventually found its way into the Community branch of MySQL starting with 5.7.8, and it works the same in both cases. While this is now old news, over the last year I’ve had a couple of inquiries from clients around super_read_only usage in MySQL, and how it works in practice. While the usage of super_read_only is not complex, there is a small caveat that occasionally leads to some confusion around its use. As such, I thought it may be a good idea to write a quick blog post explaining this feature a bit more, and expanding on how it interacts with read_only.
What is super_read_only?
For those unfamiliar, what …[Read more]