Playing aroung with mysql table migration without downtime

myql_migration_table_without_downtime.sql

/*
    More info: https://gist.github.com/bennadel/2395d7a84dda980a3ae3
*/
CREATE TABLE `friends` (
    `id` MEDIUMINT(1) unsigned NOT NULL AUTO_INCREMENT,
    `name` varchar(30) NOT NULL,
    PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=UTF8;

CREATE TABLE `friends_shadow` (
    `id` int(1) unsigned NOT NULL AUTO_INCREMENT,
    `name` varchar(30) NOT NULL,
    PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=UTF8;

ALTER TABLE `friends_shadow`
	ADD COLUMN `isBFF` tinyint(1) NOT NULL DEFAULT 0 AFTER `name`,
	ADD COLUMN `updatedAt` datetime DEFAULT NULL AFTER `isBFF`,
	ADD INDEX `IX_bestFriends` ( `isBFF` );

DELIMITER $$
  
CREATE TRIGGER `insert_friends_shadow` AFTER INSERT ON `friends`
FOR EACH ROW BEGIN

  INSERT INTO `friends_shadow`
    ( `id`, `name`, `isBFF`, `updatedAt`)
  VALUES
    ( NEW.id, NEW.name, 0, UTC_TIMESTAMP() )
  ;

END$$

CREATE TRIGGER `update_friends_shadow` AFTER UPDATE ON `friends`
FOR EACH ROW BEGIN

  UPDATE `friends_shadow`
  SET `name` = NEW.name, `updatedAt` = UTC_TIMESTAMP()
  WHERE `id` = OLD.id
  ;

END$$

CREATE TRIGGER `delete_friends_shadow` AFTER DELETE ON `friends`
FOR EACH ROW BEGIN

  DELETE FROM `friends_shadow`
  WHERE id = OLD.id
  ;

END$$

DELIMITER ;

/*
ALTER TABLE friends MODIFY id MEDIUMINT unsigned NOT NULL AUTO_INCREMENT;
ALTER TABLE friends MODIFY id BIGINT unsigned NOT NULL AUTO_INCREMENT;

RENAME TABLE
	`friends` TO `__friends_pre_migration__`,
	`friends_shadow` TO `friends`
;

DROP TRIGGER IF EXISTS `insert_friends_shadow`;
DROP TRIGGER IF EXISTS `update_friends_shadow`;
DROP TRIGGER IF EXISTS `delete_friends_shadow`;

RENAME TABLE
	`friends` TO `friends_shadow`,
	`__friends_pre_migration__` TO `friends`
;

DROP TABLE IF EXISTS friends, friends_shadow, __friends_pre_migration__;
*/