SQL Server Database is a popular way to manage database. A large number of organizations depend on SQL to organize and manage their database. If there is any damage or corruption in the database, it can be solved using SQL repair commands. Though these repair commands are quite popular for removing corruptions, But, are they really the best way to fix damaged database?
To understand this, let us discuss about this command and the impact of DBCC CHECKDB Repair_Allow_Data_Loss command in this write-up.
How DBCC CHECKDB Work
DBCC CHECKDB command is used to check SQL database consistency. The command check both physical and logical integrity of the database.
DBCC CHECKDB command ensures that your database runs smoothly without encountering any corruptions. It uses various repair commands to fix damaged SQL database. One option is of REPAIR_ALLOW_DATA_LOSS.
SQL users often take refuge to this command when they have no other option. Users also use this command in absence of a good data backup. However, this self explaining command will result in all types of data loss while mending the database. The reason is that the command will focus on removing corruption only and for that, it will remove any corruption it faces. Therefore, deleting damaged data and recovers whatever amount of healthy data is there.
ALERT! Before Running REPAIR_ALLOW_DATA_LOSS Command
- Never consider REPAIR_ALLOW_DATA_LOSS as an option if you have a good database backup. Always back up your database. Only if you do not have any healthy backup of database, run this command. Also remember that this command has a high chance of data loss, so be prepared for a considerable amount of data loss even if you have chosen to run it.
- As we have mentioned in the earlier point, this is an emergency solution. Always try to restore last known good database backup if you are having consistency issues with your database.
- Before you run this command, change the state to Emergency Mode for the database. This is a highly recommended precautionary step of this database recovery process.
- Due to the risk of data loss, try to retrieve as much data as possible from the critical database tables and other sources befor running REPAIR_ALLOW_DATA_LOSS. Save the MDF, NDF, and LDF data in a secure offsite location.
Executed REPAIR ALLOW DATA LOSS ? See What Happens
When you execute REPAIR_ALLOW_DATA_LOSS in Emergency mode, following actions will happen to your database:
- Database is recovered with the help of log-based data recovery strategies.
- If any corrupt transaction log hinders the process of database recovery, the command rebuilds the log. This abrupt log rebuilding can result in transactional inconsistencies.
- If there is an inaccessible page because of I/O checksum errors, DBCC CHECKDB ignores those pages. As a result, the chance of database recovery increases.
Looking for an alternate of REPAIR_ALLOW_DATA_LOSS ?
As we can see REPAIR_ALLOW_DATA_LOSS is the minimum level of repair option for corrupt database. It is recommended to run it as a last option to repair corrupt database as the command result in loss of data. For that users can go for SQL Recovery Tool.
This application will fix both major and minor corruptions in your SQL Server database. It recovers all deleted database objects and repair corrupted mdf successfully. It is compatible with SQL Server 2017, 2016 and all other versions of SQL.
Final Words
The blog talked about the impact of using DBCC CHECKDB with REPAIR_ALLOW_DATA_LOSS command. We have learned that the command results in data loss and should only be used when no other option is available. Users are advised to use proffessional SQL Recovery Tool to fix damaged SQL database. This application does not involve any type of data loss, and recovers corrupt SQL database mdf file. Therefore, SQL experts suggest using this program instead of running DBCC CHECKDB REPAIR_ALLOW_DATA_LOSS command.
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