MYISAM索引文件损坏的修复方法

使用MYISAM存储引擎，当创建一个表时，会出现三个文件：数据文件MYD，索引文件MYI,格式文件frm。当索引文件损坏时或者丢失时，可以用如下的方法进行修复。下面是实验过程。

[mysql@testapp74 notify]$ mv message_ignore.MYI message_ignore.MYI.bak 　　[mysql@testapp74 notify]$ 　　[mysql@testapp74 notify]$ mysqld_safe & 　　[1] 26267 　　[mysql@testapp74 notify]$ 080630 14:19:03 mysqld_safe Logging to '/usr/mysql_data/log/alert.log'. 　　080630 14:19:03 mysqld_safe Starting mysqld daemon with databases from /usr/mysql_data/data 　　[mysql@testapp74 notify]$ 　　[mysql@testapp74 notify]$ 　　[mysql@testapp74 notify]$ 　　[mysql@testapp74 notify]$ vi /usr/mysql_data/log/alert.log 　　080630 14:18:14 [Note] /usr/sbin/mysqld: Normal shutdown 　　080630 14:18:14 [Note] Event Scheduler: Purging the queue. 0 events 　　080630 14:18:16 InnoDB: Starting shutdown... 　　080630 14:18:19 InnoDB: Shutdown completed; log sequence number 162 783173592 　　080630 14:18:19 [Note] /usr/sbin/mysqld: Shutdown complete 　　080630 14:18:19 mysqld_safe mysqld from pid file /usr/mysql_data/data/testapp74.pid ended 　　080630 14:19:03 mysqld_safe Starting mysqld daemon with databases from /usr/mysql_data/data 　　080630 14:19:03 InnoDB: Started; log sequence number 162 783173592 　　080630 14:19:03 [Note] Event Scheduler: Loaded 0 events 　　080630 14:19:03 [Note] /usr/sbin/mysqld: ready for connections. 　　Version: '5.1.23-rc-community' socket: '/tmp/mysql.sock' port: 3306 MySQL Community Edition (GPL)

　　从上面可以看出，当一个表出现问题，mysql的警告日志并没有任何的错误出现。

[mysql@testapp74 notify]$ mysql -uroot 　　Welcome to the MySQL monitor. Commands end with ; or \g. 　　Your MySQL connection id is 4 　　Server version: 5.1.23-rc-community MySQL Community Edition (GPL) 　　Type 'help;' or '\h' for help. Type '\c' to clear the buffer. 　　mysql> use notify 　　Reading table information for completion of table and column names 　　You can turn off this feature to get a quicker startup with -A 　　Database changed 　　mysql> 　　mysql> 　　mysql> 　　mysql> 　　mysql> select * from message_ignore limit 1; --当查询表时，会报错 　　ERROR 1017 (HY000): Can't find file: 'message_ignore' (errno: 2) 　　mysql> check table message_ignore; 　　+-----------------------+-------+----------+----------------------------------------------+ 　　| Table | Op | Msg_type | Msg_text | 　　+-----------------------+-------+----------+----------------------------------------------+ 　　| notify.message_ignore | check | Error | Can't find file: 'message_ignore' (errno: 2) | 　　| notify.message_ignore | check | error | Corrupt | 　　+-----------------------+-------+----------+----------------------------------------------+ 　　2 rows in set (0.03 sec) 　　mysql> 　　mysql> repair table message_ignore; 　　+-----------------------+--------+----------+----------------------------------------------+ 　　| Table | Op | Msg_type | Msg_text | 　　+-----------------------+--------+----------+----------------------------------------------+ 　　| notify.message_ignore | repair | Error | Can't find file: 'message_ignore' (errno: 2) | 　　| notify.message_ignore | repair | error | Corrupt | 　　+-----------------------+--------+----------+----------------------------------------------+ 　　2 rows in set (0.00 sec)

使用格式化文件frm重新创建索引文件

mysql> repair table message_ignore USE_FRM; 　　+-----------------------+--------+----------+----------+ 　　| Table | Op | Msg_type | Msg_text | 　　+-----------------------+--------+----------+----------+ 　　| notify.message_ignore | repair | status | OK | 　　+-----------------------+--------+----------+----------+ 　　1 row in set (0.02 sec) 　　mysql> 　　mysql> check table message_ignore; 　　+-----------------------+-------+----------+----------+ 　　| Table | Op | Msg_type | Msg_text | 　　+-----------------------+-------+----------+----------+ 　　| notify.message_ignore | check | status | OK | 　　+-----------------------+-------+----------+----------+ 　　1 row in set (0.02 sec)

　　修复后，数据可以正常查询

mysql> select * from message_ignore limit 1; 　　Empty set (0.00 sec)

　　如果是格式化文件frm损坏，可以从slave拷贝过来即可，或者从备份中恢复。