Server-side incremental backups
Since we already have code to generate incremental backups, we ought to support it on for server-side backups too. In theory all this requires is for a new incremental
flag to be added to the BackupRepository
RPC (https://gitlab-org.gitlab.io/gitaly/#gitaly.BackupRepositoryRequest). This problem is that incremental backups were designed around the existing large tarball backups that backup.rake creates.
Once major downside of this is that each increment is associated with a full backup but only labelled as an integer (e.g. 001, 002, 003...). So it will be difficult to support point-in-time restores. Without this, on restore the full backup and all increments will be restored. There is no way to stop at a specific increment.