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A backup taken with Oracle's export utility is a "logical" backup, not
a "physical" backup. This mostly means that when you restore an object
from an export dump, the object is a NEW object in the database. It
gets a completely new object ID in SYS.OBJ$. To the database, it is not
the same object. This means that you won't be able to restore to a
point in time or roll forward from the time that the export was taken.
In Oracle, there are two ways to take a hot backup. The old way was to
put tablespaces in BACKUP mode and to use OS routines to copy the
datafiles. The new way is to use Oracle's backup utility, Recovery
Manager or RMAN, to perform the backup. In either case, the backup is
not "consistent." This means that there is a chance that the data in
the datafile or data block has changed between the start and the end of
the backup. Oracle uses the archived redo logs to resolve any
inconsistencies in the data. I would suggest using RMAN in Archive Log
mode to perform your hot backups.
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