Manual:User former groups table

The user_former_groups table stores the groups the user has once belonged to (will not contain groups the user had belonged to before MW 1.17). The user may again belong to these groups; check the table , if you want to know. This is used to keep MediaWiki from automatically adding users to groups from which they have been manually removed before. The table was added in.

ufg_user
Key to .

ufg_group
Name of the group, which the user was member of.

Schema summary
+---+--+--+-+-+---+ +---+--+--+-+-+---+ +---+--+--+-+-+---+
 * Field    | Type             | Null | Key | Default | Extra |
 * ufg_user | int(10) unsigned | NO   | PRI | 0       |       |
 * ufg_group | varbinary(255)  | NO   | PRI |         |       |

+---+--+--+-+-+---+ +---+--+--+-+-+---+ +---+--+--+-+-+---+
 * Field    | Type             | Null | Key | Default | Extra |
 * ufg_user | int(10) unsigned | NO   | PRI | 0       |       |
 * ufg_group | varbinary(32)   | NO   | PRI | NULL    |       |

+---+--+--+-+-+---+ +---+--+--+-+-+---+ +---+--+--+-+-+---+
 * Field    | Type             | Null | Key | Default | Extra |
 * ufg_user | int(10) unsigned | NO   | PRI | 0       |       |
 * ufg_group | varbinary(16)   | NO   | PRI | NULL    |       |

Indexes
 +++--+--+-+---+-+--++--++-+---+ +++--+--+-+---+-+--++--++-+---+ +++--+--+-+---+-+--++--++-+---+
 * Table             | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
 * user_former_groups |         0 | PRIMARY  |            1 | ufg_user    | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |
 * user_former_groups |         0 | PRIMARY  |            2 | ufg_group   | A         |           0 |     NULL | NULL   |      | BTREE      |         |               |