遭遇mediumint上限

Mediumint：The signed range is -8388608 to 8388607. The unsigned range is 0 to 16777215.

home_notification | CREATE TABLE `home_notification` (
  `id` mediumint() unsigned NOT NULL AUTO_INCREMENT,
  `uid` mediumint() unsigned NOT NULL DEFAULT '',
  `type` varchar() NOT NULL DEFAULT '',
  `new` tinyint() NOT NULL DEFAULT '',
  `authorid` mediumint() unsigned NOT NULL DEFAULT '',
  `author` varchar() NOT NULL DEFAULT '',
  `note` text NOT NULL,
  `dateline` int() unsigned NOT NULL DEFAULT '',
  `from_id` mediumint() unsigned NOT NULL DEFAULT '',
  `from_idtype` varchar() NOT NULL DEFAULT '',
  `from_num` mediumint() unsigned NOT NULL DEFAULT '',
  PRIMARY KEY (`id`),
  KEY `uid` (`uid`,`new`,`dateline`),
  KEY `from_id` (`from_id`,`from_idtype`)
) ENGINE=InnoDB AUTO_INCREMENT= DEFAULT CHARSET=utf8 |

短信息表的主键id自增到上限，第一次碰见。共13G的数据，改主键属性耗时约为1小时。