Now if they want to move out accounts to an backup database they will have to do pretty much the same work as they do with account server transfer if the purpose is to reduce the database size.
Why because you take all the tables who make up an account and his characters with their achievements and inventory together with decorated houses and move to another database.
Yes you will leave some tables in place but not much and the restore has to be totally automatic unlike an paid server transfer.
Account name and password need to be preserved same with the character names so you probably keep the user and character tables