A small analysis on MySQL database corruption and the possible resolution

MySQL is a reliable and higher secure relational database management system that was developed to deal with much bigger databases. Its improved performance, high speed and connectivity make it a better client-server application that has a support for different back-ends, client programs, and Application Programming Interfaces (APIs). But one often faces corruption issues while working with MySQL databases. The corruption may occur due to any reason, such as quitting application in the middle of a write operation, improper system shutdown, hardware issues etc. All these reasons may prevent you from accessing your important databases tables and other objects in the corrupt MySQL database. To recover back all your inaccessible and valuable data in such situations, you need to go for MySQL recovery through a reliable third party utility.

For instance, you may get an error message reading:

"Table './confluencedb/EXTRNLNKS' is marked as crashed and should be repaired"

Causes:

The possible reasons for this error message are-

You may have a limited disk space on the volume where your database is stored
Corruption in some database tables

Any type of corruption in your database may render your database inaccessible. Here, you can use a backup to recover MySQL database and get all your vital data back. You may still try to repair your corrupt database table by following the resolution steps mentioned below.

Resolution:

Follow these steps to repair your MySQL database-
Open up the Control Panel.
In 'MySQL' section, click 'REPAIR' icon against your database's name.

The above steps may help you repair all the corrupt tables in your MySQL database. If the problem still persists, you should take help of an efficient MySQL database recovery tool. These software can easily recover various database objects including tables, views, keys, constraints etc. from your corrupt MySQL database. They support both the MySQL database engines- MyISAM and InnoDB.

Stellar Phoenix MySQL Database Recovery is a comprehensive and highly secure tool that repairs damaged or corrupt MySQL tables created in MySQL 3.x, 4.x, 5.x, and 6.x versions. It enables you to preview all recoverable objects of corrupt MySQL database without even requiring a MySQL installation. It compatible with Windows 7, Vista, Server 2003, XP, and 2000.

Resource: http://www.americanchronicle.com/articles/view/218783

Rectifying Corruption Issues in MyISAM Table in MySQL 5.0.22 Database

MySQL is the most popular open-source database in the world. It has the distinction of being the only database that is used in every continent. Yes, even Antartica!!! The reasons for such popularity is its availability, performance, robustness, etc. It provides three types of database engines, MyISAM, InnoDB, and MySQL Archive. Out of these, the MyISAM table is the default table type. It is fast, simple, and allows full-text searching. Although it is reliable, it can become corrupt and, thus, inaccessible following a system crash. You should use appropriate corrective measures to repair MySQL database. However, if you are not able to do so then you should use a third-party MySQL recovery software to do so.

Consider a scenario wherein you have MySQL 5.0.22 database running in your system. You use it for MediaWiki installation that is reported as corrupt. When you try to repair the table, the following error message is displayed:

"Key in wrong position at page 4096"

You, then, quit the database and stopped the mysql process in the Task Manager and executed the myisamchk - r and myisamchk - o commands. But you were unable to resolve the issue.

Cause
The root cause of this error message is that the MySQL database is corrupt.

Resolution
To resolve this erroneous situation, you should firstly create the backup of the corrupted database. Then, you should use the following methods to repair the MySQL database:

You should use the following REPAIR TABLE query to repair the corrupted MySQL repair table tablename use_frm;

If the REPAIR TABLE query does not repair the database, then you should check for the backup. If the backup is updated and clean, then you should restore the database from its backup.

The aforementioned methods should be able to resolve the issue. However, if the problem is still there then you should use a third-party mysql repair software to restore the corrupted database. Such read-only tools are able to repair MySQL database using fast yet sophisticated scanning algorithms.

Database Recovery for MySQL is a MySQL recovery software that enables you to repair MySQL database. It is able to recover MySQL database for the MyISAM and InnoDB MySQL database storage engines. This mysql database repair tool is designed for MySQL 4.x and 5.x versions. It supports MySQL recovery for MyISAM (.myd,.myi,.frm) and InnoDB (.ibdata,.ibd,.frm) files. It is compatible with Windows 7, Vista, Server 2003, XP and Server 2000.

Advika Singh work as a freelancer and researcher repair mysql & recover mysql software.

Article Source: http://EzineArticles.com/?expert=Advika_Singh

Restore MyISAM tables by MySQL Recovery Software

Any corruption in MyISAM table is a terrible situation for Database Administrator. These MyISAM tables are the most important components in the MySQL Database to store personal as well as professional data, and the corruption in these tables may inaccessibility to the database. In this situation, a database backup allows you to restore the database and access the records in the table. Duplicate file (Backup) of the database is mostly stored on a different storage media, the changes of database corruption still exist. In that situation, you will need to perform MySQL database repair by the using of third party software.

Some error messages that enable you to identify that your MyISAM table (student) is corrupt:

“Student.frm is locked against change”
Or
“Got error message student from table handler”

Or
“Can't find file student.MYI (Errcode: nnn)”

The record saved in the student table becomes inaccessible after the above error message appears. In addition, you will receive any of the above three error messages each time when you attempt to access the table of student.

Cause of These Errors:

Few main reasons for the student table corruption are virus infection, file system damage, improper MySQL Server shutdown, human errors and many more.

How to Resolve These Errors:

To resolve above three error messages in student table and access the records, you will need to follow the below procedures:

You will have to use an in-built tool “myisamchk” to find and repair the student table records. The command-line of this tool scans the MySQL database components and found the exact cause of corruption & repairs the student tables.

You can also use several SQL commands to repair and restore the student records. Some of those commands are REPAIR TABLE, CHECK TABLE & OPTIMIZE TABLE.



The probabilities repair of student table records is very less by the using of any two above methods, but sometimes exists. Such case occurs when the student table is badly damaged at that point you (DBA administrator) will have to need advanced MySQL recovery software to repair student table.

Stellar Phoenix Database Recovery for MySQL repairs of MyISAM tables by using of advanced repairing algorithms. This software is completely read-only in nature and repairs without any modifying in the original data file. Moreover, this MySQL recovery software is easily understandable without any prior technical knowledge related to MySQL.

Source: http://hubpages.com/hub/Restore-MyISAM-tables-by-MySQL-Recovery-Software