It is pretty cool to create a restore point for the database before doing some upgrades. If upgrade fails the database can be set back to the restore point by a single statement.

CREATE RESTORE POINT before_upgrade GUARANTEE FLASHBACK DATABASE;

SELECT NAME, SCN, TIME, DATABASE_INCARNATION#, GUARANTEE_FLASHBACK_DATABASE, STORAGE_SIZE FROM V$RESTORE_POINT;

FLASHBACK DATABASE TO RESTORE POINT before_upgrade;

DROP RESTORE POINT before_upgrade;