Usually, Binary log files are located within the data directory and named in the format binlog.XXXXXX. The MySQL data directory, where database files are stored, is commonly found in the system’s MySQL installation folder (e.g., /var/lib/mysql/ on Linux systems).

Note: This process assumes you have access to the binary log files and that they were enabled on your MySQL server before the corruption occurred.

Prerequisites

1. Access to a MySQL server (doesn’t need to be the same one as crashed).
2. Binary log files (typically with names like binlog.000001).

Understanding Binary Logs

MySQL uses binary log files to record all changes to the database. These logs contain a record of every SQL statement that modifies the database, making them invaluable for data recovery purposes. By replaying these logs, you can recreate the lost or corrupted data.

Binary Logs can be read by using the mysqlbinlog command line utility provided by the default MySQL installation.

Steps to recover

1. First, login to the MySQL server as usual.

   sudo mysql

2. Create a database with the same name as the one you’re recovering.

   CREATE DATABASE <database-name>;

   

3. Run mysqlbinlog with the path to the binary log files and redirect the output to a file called temp-backup.sql

   mysqlbinlog binlog.000001 binlog.000002  > temp-backup.sql

   Note: You may have more binary log files, make sure to add them all in the above command or you may not have the full data restored.

4. Run this command so that the MySQL executes the command present in the backup file.

   mysql -u root -p < temp-backup.sql

   Note: You may need to change the parameters of -u to the user you are using. Also, you’ll be prompted for the user’s password.

5. Perform thorough checks on the recovered database to ensure data integrity. Verify the completeness and accuracy of the recovered data.

Conclusion

Recovering a MySQL database after a crash using binary logs is a complex process that requires careful attention and can result in data loss. Therefore, it is crucial to have regular backups and a well-defined recovery plan in place. If you find yourself in this situation, follow the steps outlined in this article, and make sure to consult MySQL documentation and seek expert assistance if needed.

FAQs

Q.1: Where can I find binary log files on my MySQL server?

Binary log files are usually located within the MySQL data directory, named in the format binlog.XXXXXX. The MySQL data directory is commonly found in the system’s MySQL installation folder, such as /var/lib/mysql/ on Linux systems.

Q.2: How do I know if binary logging is enabled on my MySQL server?

Binary logging is enabled by default on MySQL servers. You can check if it is enabled by running the following command:

SHOW VARIABLES LIKE 'log_bin';

If the output is ON, then binary logging is enabled.

Q.3: Why is it important to perform thorough checks on the recovered database?

It is essential to perform thorough checks on the recovered database to ensure data integrity. Sometimes things could not work as expected during recovery and you may’ve lost some data.

Q.4: Is there a better recovery procedure?

This method should be used as a last resolve when there’s nothing else that can be done. Usually, you should take regular backups using mysqldump or something similar.

Q.5: What is mysqlbinlog actually used for?

mysqlbinlog is mainly used for Point-in-Time Recovery but can also be used for normal recovery as suggested in this article.