Let's say we have a fully encrypted database (the type of encryption is not considered in this scenario), and we produce two backups for that database.

If I encrypt only one of the backups, would there be a difference between it and the other one? Is it redundant to encrypt the backup if the database was already encrypted?

I ask from the perspective of the security of the data, not performance or anything else.


  • Please add a tag for the DBMS you are asking about. – David Browne - Microsoft Jul 26 '18 at 17:11
  • 1
    It is intended as a general not vendor-specific question, but if that information is necessary to answer it, let's say it is Oracle. – Luis Jul 26 '18 at 17:19
  • Probably vendor specific, but I assume there are things besides data in an encrypted database that is not encrypted (say routines as an example). – Lennart Jul 26 '18 at 17:51

Does Rman Re-Encrypt TDE (Tablespace) Encrypted Data? (Doc ID 819167.1)

(above link requires an account associated with a valid support contract)

When using column encryption, these columns as well as other data in the tables are encrypted again during the backup. If you are using tablespace encryption these are not further encrypted during backups.


... for compressed backup on an encrypted tablespace, RMAN must decrypt all the blocks, compress them, and encrypt them using RMAN encryption ...

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