For those having trouble with mysql starting the cqrlog databases on Ubuntu:
The issue is the apparmor profile that ships with recent versions of Ubuntu is particularly restrictive. Check /var/log/syslog for the following:
Mar 16 11:01:12 ganymede kernel: [17286.306501] audit: type=1400 audit(1552748472.021:1159): apparmor="DENIED" operation="open" profile="/usr/sbin/mysqld" name="/home/mike/.config/cqrlog/database/" pid=19929 comm="mysqld" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
Recent comments