If you select a database prefix that is too long the following error is thrown:

General Error
Index name 'PREFIXXXXX_acl_groups_auth_role_id' on table 'PREFIXXXXX_acl_groups' is too long. The maximum is 30 characters.

This error should be caught when a user selects a database prefix and allowed to be solved rather than the entire installation failing and having to be redone.