mysql delete recovery

MySQL is a commonly used relational database management system. Many developers use MySQL to store and manage data. In the process of using MySQL, deleting data is a very common operation, but in some cases, mistaken deletion or accidental deletion can cause a lot of trouble. Therefore, this article will explore the recovery methods of MySQL deleted data.

1. Overview

MySQL data can be deleted through DELETE and DROP statements. The DELETE statement is usually used to delete data rows in a table, while the DROP statement is used to delete the entire table and its data. No matter which deletion method is used, once the data is deleted, it cannot be directly accessed and restored.

2. MySQL deleted data recovery method

2.1 Use MySQL Binlog to recover data

Binlog is the log of all database changes recorded by the MySQL service. Database operations are logged in binary files, including delete operations. Therefore, by viewing the Binlog file, you can find the SQL statement that deletes the data, and then restore the deleted data.

The location of the Binlog can be found through the following steps:

(1) Enter the MySQL console

(2) Enter SHOW BINARY LOGS;

(3 ) Record the results of the SHOW BINARY LOGS query, which includes the name and location of the Binlog

After finding the Binlog location, you can use the mysqlbinlog command to view the Binlog content, and use tools such as grep to find and delete SQL statements.

This method requires the MySQL Binlog function to be turned on. If it is not turned on, it cannot be used. At the same time, using Binlog to recover data requires a certain technical level and a certain degree of mastery of the MySQL command line tool and the Linux command line.

2.2 Database backup and recovery

Database backup and recovery is a very common recovery method. If you made a backup before deleting the data, you can choose to use the backup file to restore the data.

When backing up data, you can use the mysqldump command officially recommended by MySQL. This command can back up the entire database or certain tables to a file.

The following is the command to back up the MySQL database:

$ mysqldump -u username -p database name> backup file path

If you need to restore the backed up database, you can use The following command:

$ mysql -u username -p database name< backup file path

But it should be noted that if there is no backup for a long time after the data is deleted, it will be difficult to restore the data. The difficulty is greatly increased because the backup file may have expired or been deleted after the data was deleted.

2.3 Undrop-for-Innodb plug-in

Undrop-for-Innodb is a third-party plug-in that can recover deleted data to a certain extent. This plug-in needs to be used with the InnoDB storage engine and needs to be loaded when MySQL starts.

The use of this plug-in is different from regular data recovery. First, the deleted data needs to be restored based on the difference between the data insertion time and the deletion time. Therefore, if a long time has passed since the data was deleted, it will be very difficult to recover the data.

The plug-in will then create a new database upon recovery and insert the recovered data into the new database. This also means that the plug-in can only recover all data and cannot recover individual data.

But compared with other methods, this method is relatively simple and easy to use, and can restore data without backing up.

3. Summary

Deleting data in MySQL is a common operation, but mistaken or accidental deletion may lead to data loss. This article introduces several MySQL deleted data recovery methods, including using Binlog, database backup and recovery, and the third-party plug-in Undrop-for-Innodb. But no matter which method is used, you need to pay attention to factors such as recovery time and whether the data is overwritten. If you want to be able to restore data in a timely manner after data deletion, then backup is the most important thing.

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