If you are a MySQL power user in Korea, its well worth joining the Korean MySQL Power User Group. This is a group led by senior DBAs at many Korean companies. From what I gather, there is experience there using MySQL, MariaDB, Percona Server and Galera Cluster (many on various 5.5, some on 5.6, and quite a few testing 10.0). No one is using WebScaleSQL (yet?). The discussion group is rather active, and I’ve got a profile there (I get questions translated for me).