MySQL is a 'database' system that requires a command called 'repair tables' and it is pretty essential that you know how to use it. (https://dev.mysql.com/doc/refman/5.7/en/mysqlcheck.html). Actually, to be fair, it is less essential these days that it used to be. But still, if you are trusting importnat data to this system, it is a really abd sign.
(I am no expert on DB systems, but I have a strong opinion on this.)