Extension:CentralAuth/global user autocreate serial table

mysql> describe global_user_autocreate_serial;
+--------------+-------------------+------+-----+---------+-------+
| Field        | Type              | Null | Key | Default | Extra |
+--------------+-------------------+------+-----+---------+-------+
| uas_shard    | int(10) unsigned  | NO   | PRI | NULL    |       |
| uas_year     | smallint(5)       | NO   | PRI | NULL    |       |
| uas_value    | int(10) unsigned  | NO   |     | NULL    |       |
+--------------+-------------------+------+-----+---------+-------+