-- reaction
CREATE TABLE `reaction` (
  `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  `created_ts` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `creator_id` INT NOT NULL,
  `content_id` VARCHAR(256) NOT NULL,
  `reaction_type` VARCHAR(256) NOT NULL,
  UNIQUE(`creator_id`,`content_id`,`reaction_type`)  
);