```
-- Global user groups.
CREATE TABLE /*_*/global_user_groups (
gug_user int(11) not null,
gug_group varchar(255) not null,
PRIMARY KEY (gug_user,gug_group)
) /*$wgDBTableOptions*/;
CREATE INDEX /*i*/gug_user ON /*_*/global_user_groups (gug_user);
CREATE INDEX /*i*/gug_group ON /*_*/global_user_groups (gug_group);
```
The primary key indexes `gug_user` as part of the combined primary index, so a duplicate index for `gug_user` is not required
```
MariaDB [centralauth]> show indexes from global_user_groups;
+--------------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+--------------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| global_user_groups | 0 | PRIMARY | 1 | gug_user | A | 1678 | NULL | NULL | | BTREE | | |
| global_user_groups | 0 | PRIMARY | 2 | gug_group | A | 1678 | NULL | NULL | | BTREE | | |
| global_user_groups | 1 | gug_user | 1 | gug_user | A | 1678 | NULL | NULL | | BTREE | | |
| global_user_groups | 1 | gug_group | 1 | gug_group | A | 44 | NULL | NULL | | BTREE | | |
+--------------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
4 rows in set (0.00 sec)
```