maintenance/archives/patch-user_groups-ug_expiry.sql

   1 -- Primary key and expiry column in user_groups table
   2
   3 ALTER TABLE /*$wgDBprefix*/user_groups
   4   DROP INDEX ug_user_group,
   5   ADD PRIMARY KEY (ug_user, ug_group),
   6   ADD COLUMN ug_expiry varbinary(14) NULL default NULL,
   7   ADD INDEX ug_expiry (ug_expiry);