Exam 1z0-082 topic 1 question 94 discussion

"...If retention guarantee is enabled, the specified minimum undo retention is guaranteed; the database never overwrites unexpired undo data even if it means that transactions fail due to lack of space in the undo tablespace. If retention guarantee is not enabled, the database can overwrite unexpired undo when space is low, thus lowering the undo retention for the system..." Acoording to this, correct answers should be C and E.

By definition, undo extents that still have to overlive the retention period are unexpired. So, when undo_retention is set and retention is guaranteed, unexpired undo is always retained. As opposed to the case in which retention is noguarantee, where also unexpired extents can be overwritten IF and when needed. In this particolar case, so, I would say C-D are the correct answers.

The reason why option B is incorrect: Oracle has mainly two types of UNDO:

The reason why option E is incorrect: According to the Oracle Database documentation, the UNDO_RETENTION parameter specifies the minimum duration in seconds for which UNDO information for committed transactions is retained. In other words, this parameter specifies the duration for which Oracle attempts to retain UNDO data for committed transactions without expiring it. The expression "unexpired UNDO" in option E is not appropriate. The correct expressions would be "UNDO data for committed transactions" or "retaining UNDO data without expiring it." The English expression in option E, "UNDO_RETENTION specifies for how long Oracle attempts to keep unexpired UNDO," is also not appropriate. A more accurate expression would be, "UNDO_RETENTION specifies the minimum duration in seconds for which Oracle attempts to retain UNDO information for committed transactions." Therefore, option E contains problems and is not a correct expression.

A FALSE: Old (committed) undo information that is older than the current undo retention period is said to be expired and its space is available to be overwritten by new transactions. B FALSE :Undo retention period, which is the minimum amount of time that Oracle Database attempts to retain "old undo" (not all types) information before overwriting it. C TRUE: it is retained for consistent read and Oracle Flashback operations.To guarantee the success of long-running queries or Oracle Flashback operations, you can enable retention guarantee. D FALSE:When automatic undo management is enabled, there is always a current undo retention period, which is the minimum amount of time that Oracle Database attempts to retain "old undo"( not Active undo) information before overwriting it. E TRUE: If retention guarantee is enabled, then the specified minimum undo retention is guaranteed; the database never overwrites unexpired undo data even if it means that transactions fail due to lack of space in the undo tablespace.

C,E D don't related UNDO_RETENTION with GURANTEED RETENTION.

C D are correct

C and D are correct

Unexpired undo can be reused if not enough space in undo tbs , The UNDO_RETENTION parameter can only be honored if the current undo tablespace has enough space. If an active transaction requires undo space and the undo tablespace does not have available space, then the system starts reusing unexpired undo space. This action can potentially cause some queries to fail with a "snapshot too old" message. I go with D,E

Answer 1. C (always retains only unexpired undo not expired one) Answer 2. E vs. D Analysis: D: Active undo is definitely retained by undo, yes, but it is not the use/configuration of UNDO_RETENTION. Ref: https://blog.oracle48.nl/oracle-database-undo-space-explained/ E: Undo retention does specify for how long Oracle must keep unexpired undo, yes, there is (attempt) in the sentence but attempt does mean a task for a computer, unlike human a computer attempts are accurate they don't pause and say I don't want to attempt this like us when we get afraid. So, As the question demands configuration and use of UNDO_RETENTION with GUARANTEED RETENTION, The true answers are C and E

Answer 1. C (always retains only unexpired undo not expired one) Answer 2. E vs. D Analysis: D: Active undo is definitely retained by undo, yes, but it is not the use of UNDO_RETENTION. E: Undo retention does specify for how long Oracle must keep unexpired undo, yes, there is (attempt) in the sentence but attempt does mean a task for a computer, unlike human a computer attempts are accurate they don't pause and say i don't want to attempt this like us when we get afraid. So, As the question demands configuration and use of UNDO_RETENTION with GUARANTEED RETENTION, The true answers are C and E

BC is correct since undo retention is guarantee, all type of undo has to be retained event if the new undo transaction has to fail

i choose D and E for the correct answer

the question is undo retention with guaranteed retention so its C and D as unexpired undo in this case is always retained

Correct Answer: CE Wrong Answer: AB A - keep only unexpired UNDO B - not all D - true, but not described by UNDO_RETENTION, only the confirmed UNDO

I think should be DE

I bet on A, C When automatic undo management is enabled, there is always a current undo retention period, which is the minimum amount of time that Oracle Database attempts to retain old undo information before overwriting it. Old (committed) undo information that is older than the current undo retention period is said to be expired. Old undo information with an age that is less than the current undo retention period is said to be unexpired.