Trying to drop the active undo tablespace is not allowed:
FIGURE 7-5 Create Undo Tablespace confirmation
Chapter 7: Managing Transactions with Undo Tablespaces 215
SQL> drop tablespace undotbs1;
drop tablespace undotbs1
*
ERROR at line 1:
ORA-30013: undo tablespace 'UNDOTBS1' is currently in use
SQL>
The active undo tablespace must be switched with another undo tablespace before it can be
dropped. More information on switching undo tablespaces is covered later in this chapter.
Modifying Undo Tablespaces
The following operations are allowed on undo tablespaces:
Adding a datafile to an undo tablespace
Renaming a datafile in an undo tablespace
Changing an undo tablespace??™s datafile to online or offline
Beginning or ending an open tablespace backup (alter tablespace undotbs begin backup)
Enabling or disabling the undo retention guarantee
Everything else is automatically managed by Oracle.
Using OMF for Undo Tablespaces
In addition to using a bigfile tablespace for undo tablespaces, you can also use OMF to automatically
name (and locate, if you??™re not using ASM) an undo tablespace; the initialization parameter DB_
CREATE_FILE_DEST contains the location where an undo tablespace will be created if the datafile
clause is not specified in the create undo tablespace command. In the following example, we
create an undo tablespace using OMF in an ASM disk group:
SQL> show parameter db_create_file_dest
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_create_file_dest string +DATA
SQL> create undo tablespace undo_bi;
Tablespace created.
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