Q159. Which two are true about changing the LOCAL_UNDO_ENABLED property to false in a CDB? (Choose two.)
- A. After the change, only a common user with the required privilege can create an undo tablespace in CDB&ROOT.
- B. Any new PDB and existing PDBs are automatically configured to use the default undo tablespace in CDB$ROOT.
- C. After the change, only one undo tablespace can exist in CDB$ROOT.
- D. After the change, any user with the required privilege can create an undo tablespace in the PDBs.
- E. Undo tablespaces existing in PDBs must be dropped before the change.
- F. After the change, each existing PDB has to be reopened for the new undo mode to take effect.
Answer: AB
Explanation:
You can set a CDB in local UNDO mode either at CDB creation or by altering the CDB property. When the database property LOCAL_UNDO_ENABLE is FALSE, which is the default, there is only one UNDO tablespace that is created in the CDB root, and that is shared by all containers. When LOCAL_UNDO_ENABLE is TRUE, every container in the CDB uses local undo and each PDB must have its own local UNDO tablespace. To maintain ease of management and provisioning, UNDO tablespace creation happens automatically and does not require any action from the user. When a PDB is opened and an UNDO tablespace is not available, its automatically created.
Reference: https://docs.oracle.com/en/database/oracle/oracle-database/18/multi/creating-and-configuring-acdb.html#GUID-12ADA04D-F81D-4579-A68C-0958CC7D6C2F