ALTER TABLE `vn`.`workerLog` 
CHANGE COLUMN `changedModel` `changedModel` ENUM('Worker', 'workerDocument', 'Calendar', 'WorkerTimeControlMail') NOT NULL DEFAULT 'Worker',
MODIFY COLUMN changedModelId INT(11) NOT NULL,
MODIFY COLUMN oldInstance JSON NULL,
MODIFY COLUMN newInstance JSON NULL,
ADD INDEX IF NOT EXISTS `workerLog_changedModel` (`changedModel` ASC, `changedModelId` ASC, `creationDate` ASC),
ADD INDEX IF NOT EXISTS `workerLog_originFk` (`originFk` ASC, `creationDate` ASC),
DROP INDEX IF EXISTS `workerFk_idx` ;