Mysql报Cannot load from mysql.proc. The table is probably corrupted

1548-Cannot load from mysql.proc. The table is probably corrupted

http://bugs.mysql.com/bug.php?id=50183

原因是mysql.proc升级时有个字段没有升级成功。

在5.1中mysql.proc表的comment字段是varchar(64)：

  `comment` char(64) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL DEFAULT '',

但在5.5中应该是text：

 `comment` text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,   So，执行下面的语句，把这个字段修改为text，就彻底OK了： 

ALTER TABLE `proc`
MODIFY COLUMN `comment`  text CHARACTER SET utf8 COLLATE utf8_bin NOT NULL AFTER `sql_mode`;