Retention Guarantee

Retention Guarantee

If you specify the RETENTION GUARANTEE clause for theUNDO tablespace, then the database will never overwrite undo data whose age is less than the undo retention period. This functionality is new in Oracle 10g. By enabling the guarantee option, you instruct the database not to overwrite unexpired undo data even if itmeans risking failure of currently active DML operations. The clause can be specified either during undo tablespace creation time or later using an ALTER TABLESPACE command. The default setting is RETENTION NOGUARANTEE.

SQL> Alter Tablespace undotbs RETENTION GUARANTEE;

SQL>Alter Tablespace undotbs RETENTION NOGUARANTEE;

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