--- Primary key and expiry column in user_groups table
+-- Add expiry column in user_groups table
ALTER TABLE /*$wgDBprefix*/user_groups
- DROP INDEX ug_user_group,
- ADD PRIMARY KEY (ug_user, ug_group),
ADD COLUMN ug_expiry varbinary(14) NULL default NULL,
ADD INDEX ug_expiry (ug_expiry);