Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Repair table in MySQL
Answer:
If you are using the MyISAM storage engine, database might be corrupted when the computer was shutdown unexpectedly. To repair the table, you can use the following command in the MySQL client.
mysql> REPAIR TABLE my_table;
How to check the startup time of a particular program
Answer:
E.g. To check the startup time of MySQL server:
# ps -eo pid,user,cmd,lstart | grep /sbin/mysqld
3546 mysql /usr/sbin/mysqld --basedir= Tue Mar 30 21:29:12 2010
9195 root grep /sbin/mysqld Tue Mar 30 22:43:33 2010
Change MySQL replication master host
Answer:
To change the MySQL replication master host from a MySQL slave, follow the steps below.
1. Copy current master bin log file name and position
mysql> STOP SLAVE;
mysql> SHOW SLAVE STATUS\G
You will find something like the following...
Master_Log_File: mysql-bin.000081
Read_Master_Log_Pos: 3684056824
2. Change to new master using command
mysql> CHANGE MASTER TO MASTER_HOST='192.168.1.2', MASTER_LOG_FILE='mysql-bin.000081', MASTER_LOG_POS=3684056824;
mysql> START SLAVE;
Flush all MySQL log files
Answer:
MySQL default has several log files such as the error log, query log, and slow query log.
Sometimes, To perform log rotation, it is necessary to tell MySQL stop writing to these old log files, rename it and start over again.
To do so, you can execute the FLUSH LOG command in the MySQL client.
mysql> FLUSH LOG;
As a result, it will causes the MySQL to rename the current error log file with a suffix of -old and create a new empty log file.
Usually you should no need to do it manually, you should use tool such as logrotate .
Reference: http://dev.mysql.com/doc/refman/5.0/en/flush.html
Put a profile in AppArmor complain mode
Answer:
Some applications, such as the MySQL server, if you changed the default datadir, you might not be able to startup MySQL.
To solve the problem, put the MySQL profile in AppArmor complain mode can solve the problem.
# sudo aa-complain /usr/sbin/mysqld
Then reload AppArmor
# sudo invoke-rc.d apparmor reload
