Difference between full backup & level 0 incremental backup | Differential backup & cumulative backup

A level 0 incremental backup is physically identical to a full backup. The only difference is that the level 0 backup is recorded as an incremental backup in the RMAN repository, so it can be used as the parent for a level 1 backup.A full backup can never be part incremental backup strategy i.e it cannot be the parent for a subsequent incremental backup.

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Differential backup, which backs up all blocks changed after the recent incremental backup at level 1 or 0

Cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0

Note : Cumulative backups are preferable to differential backups when recovery time is more important than disk space, because during recovery each differential backup must be applied in succession. Use cumulative incremental backups instead of differential, if enough disk space is available to store cumulative incremental backups.

ORA-01555 can be avoided by following precautions:

ORA-01555 can be avoided by following precautions:

1. Database should be in Automatic Undo Management mode.
2. Use a large optimal value for undo_retention.
3. Use a large optimal size of rollback segment (undo) size.
4. Should avoid to fetch (select / cursors) between commits.
5. Should Commit less often at the time of long running query, to reduce Undo Segment slot reuse.
6. Try to run long running queries on off peak hours, when there is less DML transactions on database.