After update to Civicrm 5.8.0 I got a:
MyISAM Database Engine Your database is configured to use the MyISAM database engine. CiviCRM requires InnoDB. You will need to convert any MyISAM tables in your database to InnoDB. Using MyISAM tables will result in data integrity issues.
Is it save to do
ALTER TABLE tablename ENGINE=InnoDB;?