13.3 Restore Operations

The restore operations restores the data files from a backup to their original locations on the database server, or to other desired locations. The MySQL instance must be shut down first before a restore operation (except for backups created using transportable tablespace (TTS)). The options datadir, innodb_log_files_in_group, and innodb_log_file_size must be specified either in the target server's configuration file, in the file specified by the --defaults-file option, or as command-line options. For usage examples, see Chapter 5, Recovering or Restoring a Database.

mysqlbackup [STD-OPTIONS]
            [SERVER-REPOSITORY-OPTIONS]
            [--backup-dir=PATH]
            [--uncompress]
            [MESSAGE-LOGGING-OPTIONS]
            [PARTIAL-BACKUP-RESTORE-OPTIONS]
            [PROGRESS-REPORT-OPTIONS]
            [CLOUD-STORAGE-OPTIONS]
            copy-back

mysqlbackup [STD-OPTIONS]
            [SERVER-REPOSITORY-OPTIONS]
            [--backup-image=IMAGE]
            [--backup-dir=PATH]
            [--uncompress]
            [MESSAGE-LOGGING-OPTIONS]
            [PARTIAL-BACKUP-RESTORE-OPTIONS]
            [PROGRESS-REPORT-OPTIONS]
            [ENCRYPTION-OPTIONS]
            [CLOUD-STORAGE-OPTIONS]
            copy-back-and-apply-log

copy-back
Restores files from a directory backup to their original locations within the MySQL server.
Before restoring a hot backup using the copy-back command, the backup has to be prepared and made consistent using the apply-log command. See Section 5.1, “Preparing the Backup to be Restored” for details. You can also perform apply-log and copy-back together with a single copy-back-and-apply-log command.
Some clean-up efforts on the target directory for restoration might be needed before performing a full restore (for example, when the backup data is used to set up a new MySQL server or to replace all data of an existing MySQL server). See Section 5.2, “Performing a Restore Operation” for details.
There are some special requirements when restoring backups created with the --use-tts option; see Section 5.2.4, “Restoring Backups Created with the --use-tts Option” for details.
copy-back-and-apply-log
In a single step, restores a single-file backup specified by the --backup-image option or a backup from the directory specified by the --backup-dir option to a server's data directory and performs an apply-log operation to the restored data to bring them up-to-date. Comparing with a multi-step approach for restoring a single-file backup (which typically consists of performing the successive steps of extract, uncompress,apply-log, and copy-back for restoring compressed image, or extract ,apply-log, and copy-back for uncompressed image), the command makes the restoration process simpler and faster, and also saves the disk space required.
The following are some special requirements for different kinds of backup restoration using copy-back-and-apply-log:
- To restore a compressed directory or image, include the --uncompress option in the command line.
- To restore a single-file backup, besides specifying the location of the backup image with the --backup-image option, also supply with the --backup-dir option the location of a folder that will be used for storing temporary files produced during the restoration process.
- To restore an incremental backup directory, assuming the full backup (on which the incremental backup was based) has already been restored:
  - Include the --incremental option in the command line.
  - Use either the --backup-dir or --incremental-backup-dir option to specify the incremental backup directory.
- To restore a single-file incremental backup, besides specifying the location of the incremental backup image with the --backup-image option, also supply with the --backup-dir option the location of a folder that will be used for storing temporary files produced during the restoration process.
- To restore a backup created with the --use-tts option:
  - See the general requirements described in Section 5.2.4, “Restoring Backups Created with the --use-tts Option”.
  - When restoring a single-file backup created with the option setting use-tts=with-minimum-locking, the folder specified with --backup-dir is also used for extracting temporarily all the tables in the backup and for performing an apply-log operation to make the data up-to-date before restoring them to the server's data directory.
  - When restoring a backup directory created with the option --use-tts=with-minimum-locking, an apply-log operation will be performed on the backup directory. That means the backup taken will be altered during the process, and users might want to make an extra copy of the backup directory before proceeding with the restoration, in order to prevent the loss of backup data in case something goes wrong.
Also note that:
- Backups created with the --skip-unused-pages option cannot be restored using copy-back-and-apply-log.
- For image backups taken with MySQL Enterprise Backup 3.8.2 or earlier, per-table .ibd files pointed to by .isl files in a backup are restored by copy-back-and-apply-log to the server's data directory rather than the locations pointed to by the .isl files.
- Due to a known issue, when restoring a compressed backup created with MySQL Enterprise Backup 3.9 or earlier and containing any InnoDB tables that were created on the server as compressed tables (by using the ROW_FORMAT=COMPRESSED option, the KEY_BLOCK_SIZE= option, or both), do not use copy-back-and-apply-log; instead, perform an apply-log first, and then a copy-back. See entry for Bug# 17992297 in the MySQL Enterprise Backup 3.10.0 changelog for details.
At the end of the copy-back-and-apply-log operation, the file backup_variables.txt is being created or updated in the data directory. This file contains metadata about the restored contents and is being used by successive single-step restores of incremental backups; it should not be deleted or modified by users.
For some sample commands for restoring different kinds of backups with the copy-back-and-apply-log command, see Section 5.2, “Performing a Restore Operation”.

Warning

When restoring a server for replication purpose, if the backed-up server has used the innodb_undo_directory option to put the undo logs outside of the data directory, when using the file server-my.cnf or server-all.cnf for the --defaults-file option with copy-back or copy-back-and-apply-log, care should be taken to configure correctly the innodb_undo_directory option in the file. Otherwise, the data or log files on the original server might be overwritten by accident.