Arnaud Héritier pointed out that some of our tables run on MyISAM, and JIRA recommends us to switch to InnoDB.
I vaguely recall that he attempted this back in the days and had some troubles converting tables. See the discussion.
I recommend Arnaud to use this as an opportunity to get the local containerized JIRA development set up, then he can try converting all the tables via ALTER TABLE cwd_membership ENGINE=InnoDB; to see if any table has a problem in the way its index is set up, etc.
Once the dry-run is successful, we can make that change in production DB.