Faulty user-role mapping

[Luxter]

The mapping between user and roles is faulty with mariaDB.

2016-09-19 12:02:26.150 ERROR 5481 --- [ost-startStop-1] org.hibernate.tool.hbm2ddl.SchemaUpdate : HHH000388: Unsuccessful: create table user_roles (user_id bigint not null, roles varchar(255) not null, primary key (user_id, roles)) 2016-09-19 12:02:26.150 ERROR 5481 --- [ost-startStop-1] org.hibernate.tool.hbm2ddl.SchemaUpdate : Specified key was too long; max key length is 767 bytes

The composite key created for this relation exceeds length limit. It's probably because the composite key consists of bigint and varchar(255). Bigint takes 8 bytes and utf-8 char 3 bytes so: 8 + 255 * 3 = 773 which is greater than the 767 bytes limit.
Temporar solution was to change the enum type from EnumType.STRING to EnumType.ORDINAL (which reduced its size).