Manual:user_autocreate_serial table

The user_autocreate_serial tables is for sequential name generation for auto-created temporary users.

The segment of ID space, ID mod N, referred to by this row.

The maximum allocated ID value.

The year to which this row belongs, if the temporary account format includes the year. For IDs that are not combined with a year, this is 0.

DESCRIBEuser_autocreate_serial;

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

DESCRIBEuser_autocreate_serial;

+-----------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+------------------+------+-----+---------+-------+
| uas_shard | int(10) unsigned | NO | PRI | NULL | |
| uas_value | int(10) unsigned | NO | | NULL | |
+-----------+------------------+------+-----+---------+-------+

SHOWINDEXINuser_autocreate_serial;

+------------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Ignored |
+------------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+
| user_autocreate_serial | 0 | PRIMARY | 1 | uas_shard | A | 0 | NULL | NULL | | BTREE | | | NO |
| user_autocreate_serial | 0 | PRIMARY | 2 | uas_year | A | 0 | NULL | NULL | | BTREE | | | NO |
+------------------------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+