When we perform a partial backup using innobackupex with --include="REGEXP" option, innobackupex backups MyISAM and InnoDB tables according to regular expression passed in the option.
If we do not specify explicitely in regexp mysql db makes backup unusable for restore to clean mysql datadir.
mysql db should be backuped anyway regardless was it specified in regexp or not.
When we perform a partial backup using innobackupex with --include="REGEXP" option, innobackupex backups MyISAM and InnoDB tables according to regular expression passed in the option.
If we do not specify explicitely in regexp mysql db makes backup unusable for restore to clean mysql datadir.
mysql db should be backuped anyway regardless was it specified in regexp or not.