sql-server

Why to Repair Clustered Index in SQL Server?

A large number users of the SQL Server have to deal with a variety of problems while working with the SQL Server database. A majority of these are related to corruption of database files. As data is the essence of all the operations and forms the foundation of a company’s growth, corruption of data means that access to services and crucial information is cut off completely. The article will discuss one such corruption issue related to indexes in the database and will provide information about the methods to repair clustered index in SQL server easily.

What Causes SQL Server Clustered Index Corruption?

A clustered index can be explained as an index that rearranges the manner in which records are stored physically in a table. Every table can have a single clustered Index whose leaf nodes contain the data pages. As there can be only one order in which records are stored in the SQL Server database, it is advised to have a number of non-clustered indexes as a backup.

In the event of clustered index of the database getting corrupted, an error message will be displayed to the user which is similar to the one given below

Server: Msg 1902, Level 16, State 3, Line 1
Cannot create more than one clustered index on table
‘Table Name’. Drop the existing clustered index
‘Clustered Index Name’ before creating another.

 
Recommended Solution: For avoiding wastage of precious time and effort on manual commands, make use of a specialized software known as SQL Repair Tool to repair corrupt SQL database and Clustered Index.

Repair Clustered Index In SQL Server Manually

There is an inbuilt command named DBCC CHECKDB which is quite useful. It helps to verify and obtain information about the physical and logical integrity of the database. The syntax of this command is as given below

DBCC CHECKDB (CorruptDB) With No_InfoMsgs, All_ErrorMsgs,
TableResults;
GO

After successful execution of this command, it will give details about the database such as Object ID, Database ID, and Index ID. The index ID mapping can be interpreted as ID0=Heap, ID2= Clustered and ID1=Clustered

If IndexID value of your SQL Server database comes out to be 0 or 1, then follow the techniques given below to repair clustered index in SQL server

Technique #1: Restore From Backup

Backups can help in restoring a version of the database which worked correctly the last time it was used.In the case of data model being full or bulk-logged, it is better to take a tail-log backup in order to capture records that have not been backed up.

Technique #2: Repair Specific Pages

In order to repair a specific page, use the following command

RESTORE DATABASE DB_Name PAGE=’1:80967’ FROM DISK=’C: /DB_Name.bak’ WITH NORECOVERY

1:80967 means that the value of index ID is 1 and the page number under consideration is 80967

Technique #3: Use REPAIR_REBUILD

This command can be used to treat low levels of corruption present in the database. REPAIR_REBUILD helps to repair clustered index in SQL Server by rebuilding the contents of the database. Use the following command to achieve this purpose

DBCC CHECKDB (‘Database_Name’, REPAIR_REBUILD)

Technique #4: Repair All Pages

Use this option when there is a need to repair and remove all the errors from the database. This, however, poses a risk to the safety of data after the process has been completed.

DBCC CHECKDB (‘DB_Name’, REPAIR_ALLOW_DATA_LOSS)

If the corruption level is very high, this command will deallocate the faulty pages from memory and change all the associated links.

Shortcomings of Manual Techniques

Though the techniques discussed above can be useful they are more likely to increase the number of problems. There are a number of disadvantages connected with these methods to repair clustered index in SQL server, which are discussed below

  • Large amounts of Time is taken to execute the commands in the manual approach
  • There is a constant risk of irreversibly losing important data from the database
  • Non-technical users may find it as highly complex to implement such techniques
  • No guarantee to successfully repair clustered index in SQL server database using these methods

Conclusion

There are a number of inbuilt commands in SQL that help to remove the problem of a clustered index. Despite this, a number of issues arise while using these internal commands to achieve this goal. So, a better alternative would be to use a dedicated software solution to repair clustered index in SQL server without any further problems.

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