如何對 MySQL 進行 debug

more  /var/log/mysqld.log

080510  4:26:26 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:26:26 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:26:26 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:26:26 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:26:29 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:26:29 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:27:02 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:27:02 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:27:26 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:27:26 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:27:36 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:27:36 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:27:46 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)
080510  4:27:46 [ERROR] /usr/libexec/mysqld: Can’t open file: ‘whos_online.MYI’ (errno: 145)

在錯誤記錄檔後面有個 errno: 145，這個 145 的數字可以使用 perror 這指令來得知它代表的意思為何

直接下 perror 145

MySQL error code 145: Table was marked as crashed and should be repaired

就可得到 MySQL 給你的提示

接著就登入 MySQL 進行修復的動作

mysql> repair table whos_online;

就 OK 啦

至於 perror 是什麼咧

PERROR(1)                                                                                   MySQL Database System                                                                                  PERROR(1)

NAME
perror – explain error codes

而 perror 是包在 mysql-server 套件裡的

# rpm -qf `which perror`
mysql-server

ref: http://51cto.com/html/2005/1107/10899_2.htm