By default, a tablespace is created with NOGUARANTEE,
unless you specify the GUARANTEE keyword, either when the tablespace is created or later with
ALTER TABLESPACE:
SQL> alter tablespace undotbs1 retention guarantee;
Tablespace altered.
SQL> select tablespace_name, retention
2 from dba_tablespaces
3 where tablespace_name = 'UNDOTBS1';
TABLESPACE_NAME RETENTION
------------------------------ -----------
UNDOTBS1 GUARANTEE
Chapter 7: Managing Transactions with Undo Tablespaces 223
1 row selected.
For non-undo tablespaces, the value of RETENTION is always NOT APPLY.
Flashback Features
In this section we??™ll discuss the Flashback features supported by undo tablespaces or Flashback Data
Archive: Flashback Query, Flashback Table, Flashback Version Query, and Flashback Transaction
Query. In addition, we??™ll cover the highlights of using the DBMS_FLASHBACK package. As of
Oracle Database 11g, these features are collectively known as the Oracle Total Recall Option.
Flashback Database and Flashback Drop are covered in Chapter 14. Flashback Database
uses Flashback logs in the Flash Recovery Area instead of undo in an undo tablespace to provide
the Flashback functionality; Flashback Drop places dropped tables into a virtual recycle bin within
the tablespace and they remain there until the user retrieves it with flashback table . . . to before
drop command or empties the recycle bin, or else until the space is needed by new permanent
objects in the tablespace.
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