Ok, I was working on the staging/test database, checking out some performance problems I was experiencing.
Then I thought of optimizing one table. Optimizing should be like rebuilding the physical data file to compact record structures, remove invalidated data, …

MySQL has this OPTIMIZE TABLE command.
Ok, fire!

2/3 minutes passed. Then other 2/3. Then again.

I started to worry and tried to start new sessions, to see if table was blocked. It was.
Completely locked up.

Ok, I left the session running. Went to lunch. Came back.
Still running. WTF? I decided to interrupt the command. CTRL + C.

MySQL responded with some error code, 22 or something.
Ok, just check if I have to rebuild indexes, just in case.

SELECT * FROM sometable

Boom!

Table corrupted. No kidding. Tried to REPAIR TABLE and REPAIR TABLE QUICK.
No way. Table was completely DESTROYED.

Amazing…