Context: We would like the new columns for T339982 and T337768 to be created in production.

ALTERs to run:

ALTER TABLE ce_participants
ADD COLUMN cep_first_answer_timestamp BINARY(14) DEFAULT NULL,
ADD COLUMN cep_aggregation_timestamp BINARY(14) DEFAULT NULL;

ALTER TABLE ce_organizers
ADD COLUMN ceo_agreement_timestamp BINARY(14) DEFAULT NULL;

1. Where to run those changes: These tables are in the extension1 cluster. In particular, they can be found in the per-wiki databases of testwiki, test2wiki, and officewiki, as well as in the wikishared database. So it's a total of 4 places.
2. When to run those changes: After deployment of 1.41.0-wmf.16, next week
3. If the schema change is backwards compatible: Yes (new columns are DEFAULT NULL)
4. If the schema change has been tested already on some of the test/beta wikis: Tested locally
5. if the data should be made available on the labs replicas and/or dumps: Maybe, but we don't replicate data from x1 anyway.