How to detect and Fix Data Block Corruptions in an Oracle Database?

Published by Jacob Martin on December 4, 2013

Data block corruption in an oracle database is very usual situation but it can affect entire the database and after this type of corruption all the stored information are gets inaccessible.

We know that this database stores and maintain all the entered information by the help of data block, by the help of data blocks data can be easily fetched and manipulate by the user. So that blocks play very important role in oracle database. And if blocks gets corrupted then it corrupt all the database and its data.

What is data block corruption?

Data block corruption is the wrong in the oracle database file block. This error is very difficult to find because it not give any error message and so that oracle database is not aware of it. Database might not detect this kind of error if appropriate block checking arrangement has not been established. There are two kinds of block corruptions are classified by the Oracle database they are Logical and Physical block corruption. In logical block corruption all the content of the block is logically inconsistent, data can be easily finding by the oracle but the values are wrong. And in Physical block corruption it normally reported with ORA-1578 and corrupted blocks are doesn’t recognize by the Oracle.

Many different methods are provided by the Oracle Database for detecting and fixing the data block corruption. If any corruption is detected then you can try drop and re-create an object method but this method is not possible always so it is not famous among the database users. You can also try to rebuild the table by selecting all data excluding the corrupt rows. Try some given commands to detect the block corruption.

VALIDATE STRUCTURE– Under this command or method every single block of data are verified in the analyzed object and during this process if any corruption are found then the corrupted rows are added to INVALID_ROWS table.

DBVerify– It is and external command that enable the validation of offline data files, it can also able to checking validation of the backup files. It is one of the best external command provided by the Oracle database.

DB_BLOCK_CHECKING– This external command require some arguments so that it may add extra overhead to database server and this command is apply only when you can accept an extra overhead.

DBMS_REPAIR– By applying this command you can detect and fix any database corruption, it requires two administrations first is the Oracle database table which is used to hold the total list of damaged blocks and second is the indexed key which points to corrupted blocks.

Causes of Block Corruption:

• Due to bad permissions of CDUMP, BDUMP or UDUMP directories • Due to missing data-files • Due to data corruption • Try to renaming files when Oracle is down • Due to Hardware and software malfunctioning. • Due to operating system errors. • Because of any virus attack. • Improper system shut down. • Unacceptable Database closing. • Media corruption or damage can affect database. • Block corruption can occurs due to sudden occurrence of memory    error.

• Network failure while database is open.

If you are not able to apply any manual method in the manner to repair and recover corrupted blocks of Oracle database, then you can try any third party oracle database repair tool. This tool is for those users that doesn’t have technical knowledge or unable to repair and recover their corrupted oracle database. This tool is specially designed for the normal users, design of this tool is suitable for the normal users. Along with its design it is also very fast and efficient tool that can able to repair and recover any kind of block errors. By the help of this tool you can recover entire database and can also able to recover any huge database.

It is specially designed to repair and recover any corrupted oracle database file and it will also helps in restoring username and tables. Along with oracle database it can also recover queries of the database. This tool also supports XML data and XML schemes recovery with columns in tables.

Steps to Fix Data Block Corruptions in an Oracle Database

Steps to fix Corrupted Oracle Table

Step 1: Search Initial screen of Stellar Phoenix Oracle Recovery with a pop-up window showing options to select or search corrupt Oracle databases in your computer.

Step 2: Click Scan File to initiate the scan process after selecting the oracle database. The recoverable database objects get listed in left-side pane.

Step 3: Click an object to see its preview.

Step 4: : Click Start Repair in the icon bar to start the repair process. A pop-up window is displayed which show the steps needed to perform further. Click next and continue.

Step 5: Give the user name, password and path of the blank database where you want to save the repaired database objects.

Step 6: Repairing and restoring various database objects after establishing a connection with blank oracle database.