subject: Application Or Server Crash Causes Mysql Database Corruption [print this page] Every version of MySQL RDBMS is launched after testing on various platforms. However, it can not be guaranteed that it does not have any bug. The application may have various bugs that are pretty difficult to discover. You may see various symptoms of these bugs, which include frequent application crashing and system freezing. Application crash like problem may damage the precious data in your database and lead to severe data loss. In such situations, MySQL recovery becomes need of hour to get your precious data back.
The very first step that you need to take to find out the cause of application crash is, check whether the mysqld server dies or the problem is associated with the client. You can also check how long the server remains up when you execute the mysqladmin version. If mysqld server is dead and rebooted, you can identify the root of this problem by examining error log of the server.
Cause of MySQL Server Crash:
Most of the server crashes are generally caused by the damaged index files of the database or the database itself. MySQL updates files on the hard drive with write() system call after executing any SQL statement and before client is notified regarding the results. Generally server crash doesn't cause database corruption if any of the below conditions are true:
The MySQL server update was killed halfway.
There is a bug in the mysqld server that kills the update.
External applications are manipulating the index files or data files simultaneously to the mysqld without properly locking the tables.
There is a crashed index or data file that holds damaged information which lead to a confused mysqld server.
Data storage code has some bugs. Though unlikely, it is possible. Here you may try changing the database storage engine with the help of ALTER TABLE command.
When database corruption occurs, you have to recover MySQL database from an updated and valid backup to get your mission-critical data back. However, if there is a clean and current backup in place, MySQL repair software becomes need of the hour.
These applications repair MySQL database by thoroughly scanning it using high-end scanning techniques. With simple and attractive graphical user interface, they do not demand sound technical skills to extract corrupt data from MySQL database.
Stellar Phoenix Database Recovery for MySQL is the best database recovery software which ensures perfect recovery of corrupt MySQL database. The software works well with MySQL 5.x and 4.x. It recovers both MyISAM and InnoDB storage engine-based databases.
