How to Rebuild Transaction Log in SQL Server with Corrupted or Deleted Data?

The transaction logs are one of the crucial components of SQL Server. However, trouble occurs when users accidentally delete this file or it gets corrupted. This is exactly when users need to learn how to rebuild transaction log in SQL Server for deleted or corrupted data records. Evidently, this article is going to address this problem despite the causes like hardware issues, accidental deletion, malware, etc.

Before we proceed, users must understand that transaction log files of the SQL Server are quite significant. Log files store the details of all the SQL transactions by each & every user. This log helps in maintaining indexes, recovering lost data, tracking who modified data for auditing purposes, etc. Thus, it is mandatory to restore transaction log SQL Server DB.

To understand the entire operation, we have to go through the causes of corruption, troubleshooting steps, & solutions. In addition, do not miss out on the keynotes at the end.

Why Does SQL Transactional Log Files Catch Corruption?

• Cyber Attacks – Malware, ransomware, types of SQL injection attacks, etc threats often cause the log file to corrupt. This is because attacks are well aware that users only back up MDF but forget about the log files.
• Accidental Deletion – Another common issue is accidental deletion. The rollback command is useful for primary data. However, in the case of log files, users get confused about the technicalities.
• SQL Version Issues – A lot of users do not verify the compatibility of the log files & the SQL Server versions. This happens to be one of the reasons why users need to SQL rebuild transaction log records.
• Fragmented I/O Operations – Power outages & sudden system shutdowns cause an interruption in the I/O operation. Thus, it reflects the same problem in the log files that display various log-related errors to users.
• Issues in the I/O Subsystem – Inadequate space in the drive where log files are stored is trouble too. Issues in the hard disk where the SQL server is hosted make the situation worse than ever.
• Heavy Log Files (Large Size) – Keeping large-sized log files is not a good practice to follow. Users must focus on keeping the files short as much as possible to avoid corruption issues in the log records.
• SQL Server Account Changes – last but not least, any changes in the SQL 

Apart from these reasons, there can be plenty of other causes that differ from user to user & case to case. However, we have now covered the majority of them to provide users with an idea of the potential root cause.

Troubleshoot Transaction Log Deletion & Damage

Now, users must cross-verify if the log files are deleted or corrupted. To check, bring the database online if it is in offline or suspect mode. Thus, if users face the below issues, they can be positive about the doubt of corruption issues. Then, it is mandatory to rebuild transaction log in SQL Server DB.

1. Getting the file activation error. Diagnose & rectify the errors in case the ‘C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\DATA\XXX.ldf’ is not correct.
2. In case, users are getting I/O errors, run a consistency check of the complete database. The error might look like this “incorrect checksum (expected: 0x186ba635; actual: 0x186b2635)” or related.
3. In case the system gets shutdown during a running transaction, there will be a high chance of corruption. Users will face issues in rebuilding the log files also. Thus, manual solutions won’t work.

Rebuild Transaction Log in SQL Server – Top 3 Ways

To fix the corruption or bring back the database files from corruption, we have the top 3 ways. Users will get the solution for sure by using any one of these methods. Here. we have to fix the problem by restoring the transaction log from a backup file, rebuilding from the start, or using an automated solution. Users can select any of these solutions based on their requirements. Also, not all users are eligible for every solution because of certain conditions. Let’s understand these solutions in depth.

#1 Restore Transaction Log SQL Server from Backup

1. Launch the SSMS(SQL Server Management Studio) in the system.
2. Right-click the desired database & Hit the Restore Database option.
3. Enter the Path of Backup in the Source section of the General page.
4. From the Drop-Down Menu, Select the desired Database Backup.
5. Now, Select the Database users want to restore using the BAK file.
6. Set “To the last backup taken” option in the Restore To settings.
7. Choose the Backups to rebuild from Backup Sets to Restore option.
8. At last, Click on the Ok button to complete the operation.

Note: If users don’t have a backup file of the database, this method is not possible for them.

#2 SQL Server Rebuild Transaction Log File

Users might not have a backup file or they are uncomfortable with the above method. Therefore, they can select this method where they have to rebuild the entire log files. This is the only way possible to rebuild records manually.

Step 1. Navigate to the Log File Path in the System

Users can navigate with two ways:

1. T-SQL Query:
   

   SELECT name AS 'LogicalFileName',
   physical_name AS 'FilePath'
   FROM sys.master_files

2. SSMS Method:
   

   Right Click Database >> Properties >> Files >> Log File Path

Step 2. Rebuild Transaction Log in SQL Server

Run the command or follow steps to detach the files from the server first:

USE [master]
GO
EXEC master.dbo .sp detach db @database_name = N‘test’

OR

USE [master]
GO
ALTER DATABASE [test] SET OFFLINE
GO

SSMS Steps:

Open SSMS >> Right-click Database >> Tasks >> Detach

OR

Open SSMS >> Right-click Database >> Tasks >> Take Offline

Step 3. Create New Database Based to Rebuild Complete Data.

CREATE DATABASE database_name
ON (FILENAME = ‘c:\database.mdf
FOR_ATTACH_REBUILD_LOG ;

Step 4. Create New Database Based to Rebuild Complete Data.

ALTER DATABASE database_name
MODIFY FILE (
NAME = ‘database_old_name’
NEW NAME = ‘database_new_name’

ALTER DATABASE database_name
ADD LOG FILE (
NAME = ‘database_new_name’
FILENAME = ‘new_database_log.ldf’,
SIZE = 128MB,
MAXSIZE = UNLIMITED,
FILEGROWTH = 128MB
);

Finally, users will see the new log files just as before. In case, users find this method quite technical, they can switch to the modern method mentioned below.

#3 Automated Software to Fix All Log Issues

To avoid all the hassles & easily execute SQL Server rebuild transaction log file, download the expert-recommended Best SQL Log Analyzer Tool. This advanced utility allows users to rebuild as well as repair LDF file without hassles.

The software comes with these major features mentioned below:

• Examination of log files
• Quick & Advance Scan
• Multiple Export options
• Schema & Data Repair
• Result customization

Learn the steps from the video below:

Step-by-Step Procedure of Automated Tool

Now, to understand the entire process to restore transaction log SQL Server quickly, here are the steps mentioned:

Step-1. Launch the Analyzer & then Hit the Open button to rebuild.

Step-2. Select the Offline or Online option for the rebuild task.

Step-3. Upload the Log File from the system’s source path.

Step-4. Preview the Log records from the uploaded files.

Step-5. Finish SQL Server Rebuild Transaction log file.

Key Notes for SQL Rebuild Transaction Log

Now, users must take care of a few key notes. This can help them rebuild the log file as well as prevent this trouble from happening.

Key Notes

• Make sure to keep a backup of the entire database. In fact, users must practise frequent backup habits of the database to fix such issues.
• Use the demo version of the automated tool to check if it is working for your SQL server. The tool works 99.99% of the time for SQL Server rebuild transaction log.

Preventive Tips

• Maintain proper indexes in the SQL Server to avoid log file errors. Index & log file issues are complementary to each other.
• Regular SQL primary data, secondary data & log data audit can help identify the errors in the early stages. Frequent monitoring actually works a lot.

Conclusion

Finally, after discussing all the concerned topics, users can easily rebuild transaction log in SQL Server with deleted or corrupted data files. However, it is equally important for all to know the causes, tips, & other secondary factors as the solution itself.

To save the extra time & effort required for the manual ways, the automated solution in the best. This is why IT experts & SQL MVPs recommend this as it saves time & resources along with better accuracy. Otherwise, users are free to make their own decision for SQL the Server rebuild transaction log task.

FAQs

Q-1. Can we fix MDF files with this SQL Log explorer tool?

Ans: No, this software only works for the log files. However, users can trust the SQL Database Recovery Tool to fix MDF & NDF issues.

Q-2. Is Repair_Allow_Data_Loss command helpful to rebuild log file records?

Ans: No, There is no guarantee of this command to provide desired results. Instead, Repair_Rebuild command can work perfectly for learning how to rebuild transaction log in SQL Server with corrupted or deleted records.

Q-3. How do I clean up SQL transaction log?

Ans: Users can follow several strategies to clean up the transaction log as mentioned below:

• Shrink Log file
• Optimize Indexes
• Regular Log backups
• Limit Log Auto Growth
• Monetize Log Space Usage