Monday, May 10, 2010

MySQLD Read/Write Process Interrupted

MySQL Server (MySQLD) is an important program that performs almost all operations during a MySQL installation. The server is also responsible for managing and accessing records that are saved in MySQL data directory. This directory contains all the necessary information, such as, databases, tables, log files, and status files that are required by the user. Interruption in MySQLD process while it is performing some read or write operation on any MyISAM table results into corruption of that table. In such cases, the user encounters an error message while accessing the corrupted table, further resulting in inaccessibility of data saved in that table. To surmount such table corruption error messages, you need to restore data from an updated backup. However, if no backup of the table is available, then the user needs to repair the table using advanced MySQL Repair utility.

Consider a practical scenario, where you run an update command on a MyISAM table. While the MySQLD was performing the updates, it crashed in between due to power outage. However, next time you try to open that table, you encounter below error message:

“Incorrect key file for table: '...'. Try to repair it”

The error message means that the MyISAM table is corrupt. The message repeatedly occurs each time you try to access the database.


The main cause of corruption is killing of MySQLD process while performing a write operation.


To resolve MyISAM table corruption and to access the data saved in it, you need to:

Run 'CHECK TABLE' command to verify the health of MyISAM table.
Next, run 'REPAIR TABLE' command to repair the corrupt MyISAM table.

While the above steps successfully repair most corrupted MyISAM tables, there are still some situations where these steps fail to repair. For such scenarios, you need to opt for an effective third-party MySQL Repair application. A Repair MySQL Database utility provides complete MyISAM table repair using advanced repair algorithms.

MySQL successfully repairs logically corrupted MyISAM table in only three steps. The MySQL Database Repair utility also repairs InnoDB tables. The utility provides risk-free repair as it does not makes any change in the tables. Supported by MySQL 5.x and 4.x, the tool can be installed on Windows 7, Vista, XP, 2003 and 2000 operating systems.

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