Diff of vagrant->prod: CREATE TABLE `bug_job_map` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `bug_id` int(10) unsigned NOT NULL, `created` datetime(6) NOT NULL, `job_id` bigint(20) NOT NULL, - `user_id` int(11), + `user_id` int(11) DEFAULT NULL, PRIMARY KEY (`id`), UNIQUE KEY `<NAME>` (`job_id`,`bug_id`), KEY `<NAME>` (`bug_id`), KEY `<NAME>` (`user_id`), CONSTRAINT `<NAME>` FOREIGN KEY (`job_id`) REFERENCES `job` (`id`), CONSTRAINT `<NAME>` FOREIGN KEY (`user_id`) REFERENCES `auth_user` (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;

The difference is a no-op really, since an unspecified default for this field type is the same as a DEFAULT NULL, but for the sake of easing schema comparisons, I've run this against dev/stage/prod: ALTER TABLE `treeherder`.`bug_job_map` ALTER COLUMN `user_id` DROP DEFAULT;