Once https://gerrit.wikimedia.org/r/328377 and its various dependencies are merged, there will need to be schema changes on Wikimedia wikis.
* The ALTER TABLES to run: https://gerrit.wikimedia.org/r/#/c/328377/19/maintenance/archives/patch-user_groups-ug_expiry.sql
* Where to run those changes: All wikis
* When to run those changes: I'll mark this as #blocked-on-schema-change after all relevant code patches are merged and testing has been completed on the beta cluster. Then it can be done at any time.
* If the schema change is backwards compatible: Yes. The feature is temporarily disabled by a feature flag.
* If the schema change has been tested already on some of the test/beta wikis: To do
* If it involves new columns or tables, if the data should be made available on the labs replicas: Yes, the new ug_expiry column is public data