Create Undo Tablespace

Syntax:

CREATE UNDO TABLESPACE tbs_name
DATAFILE 'filename' SIZE {KMG}
[AUTOEXTEND {OFF ON} [NEXT int {KM}] [MAXSIZE int {KM}] ]
[EXTENT MANAGEMENT {DICTIONARY LOCAL {AUTOALLOCATE UNIFORM [SIZE int K M]} }]
[RETENTION NOGUARANTEE GUARANTEE];

Note: The Autoextend MAXSIZE will default to UNLIMITED if not specified.


Example:

CREATE UNDO TABLESPACE undotbs1
DATAFILE 'oracle/prod/datafile/undotbs1' SIZE 5000M
AUTOEXTEND ON NEXT 5M MAXSIZE UNLIMITED
EXTENT MANAGEMENT LOCAL
RETENTION NOGUARANTEE;

When you start the instance, the database automatically selects the first available undo tablespace. If no undo tablespace is available, the instance stores the undo records in the system tablespace.

If the tablespace mentioned in the UNDO_TABLESPACE parameter does not exist, then the startup command will fail.

Thanks