How to recover deleted data files in mysql

When the MySQL data file is accidentally deleted, the recovery method depends on the situation: when the binary log is enabled, SQL statements can be retrieved through the mysqlbinlog command. If a backup exists, you can use recovery tools to restore your files. If there is no backup, you can try to use the data dictionary to restore the file: query the innodb_table_stats table to obtain metadata. Copies the deleted .ibd file header and overwrites the tablespace .ibd file header. Restart the MySQL server to reload the file.

How to recover deleted data files in MySQL

When you accidentally delete important MySQL data files , restoring them is crucial. This tutorial will guide you through the recovery process step by step.

Step 1: Check the binary log

If the binary log was enabled before deletion, you can retrieve the SQL statement for the deleted data using the following command:

<code>mysqlbinlog --start-datetime="YYYY-MM-DD HH:MM:SS" --stop-datetime="YYYY-MM-DD HH:MM:SS" /path/to/binary-log-file | grep 'table_name'</code>

Step 2: Use a recovery tool

If you did not enable binary logging, you can use a recovery tool such as MySQL Enterprise Backup or Percona XtraBackup to recover files from a backup. Make sure you have backups that are granular enough to allow you to restore affected files.

Step 3: Use data dictionary to restore files

If the above method is not feasible, you can try to use data dictionary to restore files. This method relies on the table structure and data still existing in the data dictionary table.

1. Connect to the MySQL server and access the information schema database:

<code>mysql -u <username> -p
USE information_schema;</username></code>

2. Query the innodb_table_stats table to get metadata for deleted files:

<code>SELECT table_name, data_file_pos FROM innodb_table_stats WHERE table_id = <table_id>;</table_id></code>

3. Determine the location of the .ibd file that contains the deleted data.
4. Copy the header of the .ibd file, which contains file metadata.
5. Locate the tablespace .ibd file containing deleted data.
6. Use the dd command to copy the header of the .ibd file to the table space .ibd file:

<code>dd if=<deleted_ibd_file_path> of=<table_space_ibd_file_path> bs=512 count=2048</table_space_ibd_file_path></deleted_ibd_file_path></code>

7. Restart the MySQL server so that MySQL can reload the tablespace .ibd file.

Note:

• Recovering deleted files may take time and resources.
• Always perform regular backups to ensure that you can recover your data in the event of data loss.
• Consult your database administrator or technical expert before performing recovery.

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