ALTER TABLE .. DEFAULT CHARSET does not work

drop table if exists t1;

create table t1 (a timestamp) engine=Columnstore default charset=utf8;

alter table t1 default charset=utf8;

MariaDB [db]> create table t1 (a timestamp) engine=Columnstore default charset=utf8;

Query OK, 0 rows affected (0.574 sec)

MariaDB [db]> alter table t1 default charset=utf8;

ERROR 1178 (42000): The storage engine for the table doesn't support The syntax or the data type(s) is not supported by Columnstore. Please check the Columnstore syntax guide for supported syntax or data types.