So I stop the mysql process and then for the sake of recoverability, I tar
up /var/lib/mysql/mywiki into a file called mywiki_without_new_data.tar.
I then rm -rf /var/lib/mysql/mywiki and then untar the
mywiki_with_new_data.tar in it's place. MariaDB will no longer start. If
I again rm -rf /var/lib/mysql/mywiki and then untar
mywiki_without_new_data.tar into the location, MariaDB starts without
error.
This isn't a code blue situation, my friend can recreate the change he
made and that is the easiest solution, but others reading this might not
have that luxury. I am also quite curious about what went wrong and how
to repair the problem. I didn't think this was possible to fail.
There is an interesting except from the errors described below. I'm not
certain what exactly this means, or how to correct it. Given that MariaDB
could have failed uncleanly when the mysql database was imported, recovery
may be infeasible. (the wiki connected to MariaDB as root, it's bad, I
know)
<excerpt /var/lib/mysql/altdorf.err>
InnoDB: Error: tablespace id is 235 in the data dictionary
InnoDB: but in file ./mywiki/objectcache.ibd it is 254!
2017-06-07 11:45:08 5c7ff420 InnoDB: Assertion failure in thread
1551889440 in file fil0fil.cc line 638
InnoDB: We intentionally generate a memory trap.
</excerpt>
