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Oracle

1Z0-062 · Question #139

Examine the parameters for your database instance: You execute the following command: SQL> ALTER TABLESPACE undotbs1 RETENTION NOGUARANTEE; Which statement is true in this scenario?

The correct answer is D. An attempt is made to keep inactive undo for 1200 seconds but transactions may overwrite the. With RETENTION NOGUARANTEE, Oracle makes a best-effort attempt to keep inactive undo data for the UNDO_RETENTION period (1200 seconds) but will allow new transactions to overwrite it if the undo tablespace is under space pressure.

Managing Undo Data

Question

Examine the parameters for your database instance:

You execute the following command:

SQL> ALTER TABLESPACE undotbs1 RETENTION NOGUARANTEE; Which statement is true in this scenario?

Options

  • AUndo data is written to flashback logs after 1200 seconds.
  • BInactive undo data is retained for 1200 seconds even if subsequent transactions fail due to lack of
  • CYou can perform a Flashback Database operation only within the duration of 1200 seconds.
  • DAn attempt is made to keep inactive undo for 1200 seconds but transactions may overwrite the

How the community answered

(67 responses)
  • A
    4% (3)
  • B
    1% (1)
  • C
    7% (5)
  • D
    87% (58)

Why each option

With RETENTION NOGUARANTEE, Oracle makes a best-effort attempt to keep inactive undo data for the UNDO_RETENTION period (1200 seconds) but will allow new transactions to overwrite it if the undo tablespace is under space pressure.

AUndo data is written to flashback logs after 1200 seconds.

Undo data is stored in the undo tablespace, not in flashback logs; flashback logs are written by the flashback logging mechanism and are entirely separate from undo management.

BInactive undo data is retained for 1200 seconds even if subsequent transactions fail due to lack of

It is RETENTION GUARANTEE - not NOGUARANTEE - that prevents unexpired undo from being overwritten even if new transactions fail as a result of insufficient space in the undo tablespace.

CYou can perform a Flashback Database operation only within the duration of 1200 seconds.

The Flashback Database feature depends on flashback log availability and the DB_FLASHBACK_RETENTION_TARGET parameter, not on UNDO_RETENTION or the retention mode of the undo tablespace.

DAn attempt is made to keep inactive undo for 1200 seconds but transactions may overwrite theCorrect

RETENTION NOGUARANTEE is the default mode and means Oracle tries to honor the UNDO_RETENTION setting (1200 seconds in this scenario) but does not enforce it strictly. If the undo tablespace has insufficient free space, the system will overwrite unexpired undo segments to accommodate new transactions, prioritizing transaction success over undo preservation.

Concept tested: Undo retention NOGUARANTEE mode and UNDO_RETENTION behavior

Source: https://docs.oracle.com/en/database/oracle/oracle-database/19/admin/managing-undo.html

Topics

#undo tablespace#UNDO_RETENTION#RETENTION NOGUARANTEE#undo management

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