Which statement is true regarding undo tablespace?
A.
Undo tablespace Is a temporary tablespace.
B.
Only one undo tablespace can exist in a database.
C.
Undo tablespace can consist of only one data file that is reused in a cyclic fashion.
D.
Multiple undo tablespaces can exist in a database but only one can be active at a lime.
Explanation:
A,D
Please do not leave answers unless you are sure of the answer.
A is, most certainly, not correct as per Oracle documentation:
https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_7003.htm
“An undo tablespace is a type of permanent tablespace used by Oracle Database to manage undo data”
D is correct:
https://docs.oracle.com/cd/B19306_01/server.102/b14231/undo.htm
“When the instance starts, the database automatically selects the first available undo tablespace. If no undo tablespace is available, then the instance starts without an undo tablespace and stores undo records in the SYSTEM tablespace. This is not recommended in normal circumstances, and an alert message is written to the alert log file to warn that the system is running without an undo tablespace.
If the database contains multiple undo tablespaces, you can optionally specify at startup that you want to use a specific undo tablespace. This is done by setting the UNDO_TABLESPACE initialization parameter”