1Z0-062 · Question #139
1Z0-062 Question #139: Real Exam Question with Answer & Explanation
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.
Question
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
Explanation
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.
Common mistakes.
- A. 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.
- B. 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.
- C. 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.
Concept tested. Undo retention NOGUARANTEE mode and UNDO_RETENTION behavior
Reference. https://docs.oracle.com/en/database/oracle/oracle-database/19/admin/managing-undo.html
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