TiDB Incremental Backup and Restore Guide

Incremental data of a TiDB cluster is differentiated data between the starting snapshot and the end snapshot of time period, and the DDLs generated during this period. Compared with full (snapshot) backup data, incremental data is smaller and therefore it is a supplementary to snapshot backup, which reduces the volume of backup data. To perform incremental backup, ensure that MVCC data generated within the specified period is not garbage collected by the TiDB GC mechanism. For example, to perform incremental backup hourly, you must set tidb_gc_life_time to a value greater than 1 hour.

Limitations

Because restoring the incremental backup relies on the snapshot of the database table at the backup time point to filter incremental DDL statements, the tables deleted during the incremental backup process might still exist after the data restore and need to be manually deleted.

The incremental backup does not support batch renaming of tables. If batch renaming of tables occurs during the incremental backup process, the data restore might fail. It is recommended to perform a full backup after batch renaming tables, and use the latest full backup to replace the incremental data during restore.

Starting from v8.3.0, the --allow-pitr-from-incremental configuration parameter is introduced to control whether incremental backups and subsequent log backups are compatible. The default value is true, which means that incremental backups are compatible with subsequent log backups.

• When you keep the default value true, the DDLs that need to be replayed are strictly checked before the incremental restore begins. This mode does not yet support ADD INDEX, MODIFY COLUMN, or REORG PARTITION. If you want to use incremental backups together with log backups, make sure that none of the preceding DDLs exist during the incremental backup process. Otherwise, these three DDLs cannot be replayed correctly.

• If you want to use incremental restores without log backups during the whole recovery process, you can set --allow-pitr-from-incremental to false to skip the checks in the incremental recovery phase.

Back up incremental data

To back up incremental data, run the tiup br backup command with the last backup timestamp --lastbackupts specified. In this way, br command-line tool automatically backs up incremental data generated between lastbackupts and the current time. To get --lastbackupts, run the validate command. The following is an example:

LAST_BACKUP_TS=`tiup br validate decode --field="end-version" --storage "s3://backup-101/snapshot-202209081330?access-key=${access-key}&secret-access-key=${secret-access-key}"| tail -n1`

The following command backs up the incremental data between (LAST_BACKUP_TS, current PD timestamp] and the DDLs generated during this time period:

tiup br backup full --pd "${PD_IP}:2379" \
--storage "s3://backup-101/snapshot-202209081330/incr?access-key=${access-key}&secret-access-key=${secret-access-key}" \
--lastbackupts ${LAST_BACKUP_TS} \
--ratelimit 128

• --lastbackupts: The last backup timestamp.
• --ratelimit: The maximum speed per TiKV performing backup tasks (in MiB/s).
• storage: The storage path of backup data. You need to save the incremental backup data under a different path from the previous snapshot backup. In the preceding example, incremental backup data is saved in the incr directory under the full backup data. For details, see URI Formats of External Storage Services.

Restore incremental data

When restoring incremental data, make sure that all the data backed up before LAST_BACKUP_TS has been restored to the target cluster. Also, because incremental restore updates data, you need to ensure that there are no other writes during the restore. Otherwise, conflicts might occur.

The following command restores the full backup data stored in the backup-101/snapshot-202209081330 directory:

tiup br restore full --pd "${PD_IP}:2379" \
--storage "s3://backup-101/snapshot-202209081330?access-key=${access-key}&secret-access-key=${secret-access-key}"

The following command restores the incremental backup data stored in the backup-101/snapshot-202209081330/incr directory:

tiup br restore full --pd "${PD_IP}:2379" \
--storage "s3://backup-101/snapshot-202209081330/incr?access-key=${access-key}&secret-access-key=${secret-access-key}"