Incremental Backup

An incremental backup is designed to save storage space and to run more quickly than a full backup by only saving what has changed since a "base" event, where the default base is the most recent backup or restore event. TigerGraph’s incremental backup feature also has an option to let you specify a backup tag other the default base.

Incremental backups are related to but different than differential backups. A different backup saves since the most recent backup or restore event.

Internally, incremental backup saves the Kafka messages that have changed since the base event.

Example:

At midnight every day, you run a backup. On Sunday nights, it is a full backup. On other nights, it is an incremental backup. Assume January 1 was a Sunday. The list below are the tags for your first four backups of the year.

full-weekly-jan-01 // contains a full backup
incr-daily-jan-02  // contains only what changed on Jan. 2
incr-daily-jan-03  // contains only what changed on Jan. 3
incr-daily-jan-04  // contains only waht changed on Jan. 4

In general, the incremental backup files will be much smaller than the full backup file. While the full backup file is proportional to the size of your database, the incremental backup files are proportional to the amount of change that occurred.

Run an Incremental Backup

Adding the --incremental to the backup command creates an incremental backup whose base is the most recent backup, full or incremental.

gadmin backup create <tag> --incremental

Prior to version 4.2, the --incremental flag actually performed a differential backup.

Specify the base

The --base option causes the incremental backup to be based on a backup other than the most recently one:

gadmin backup create <tag> --incremental --base <existing_backup_tag>

Differential backup can be emulated by using

--base <recent_full_backup_tag>

Identify Full and Incremental Backups

The output display from gadmin backup list distinguishes between Full and Incremental backups:

gadmin backup list
backup list
Figure 1. gadmin backup list example result.

Restore to an Incremental Backup Point

Restore uses the same command, whether you are restoring a full backup or an incremental backup. However, eacn restore operation only handles the data that it backed up. Therefore, you need to run a sequence of restore operations, in the same chronological order of the backups, to get back to the desired point.

Example:

Suppose you made the following backups, at the times indicated by these tags:

full-weekly-jan-01
incr-daily-jan-02
incr-daily-jan-03
incr-daily-jan-04

If you want to restore to January 3, then you need to run the following sequence of restore operations:

gadmin backup restore full-weekly-jan-01
gadmin backup restore incr-daily-jan-02
gadmin backup restore incr-daily-jan-03

Limitations

Differential backup does have some know limitations:

  • The base backup for an incremental backup cannot be for a time point before the most recent restore.

  • Incremental backup cannot be performed if a Point-in-Time Restore occurred since the most recent full backup. Perform another full backup first.

  • Incremental backup can only restore to a cluster that has the same partitioning factor as the cluster it backed up.