Examine the parameters for your database instance:
Which three statements are true about the process of automatic optimization by using cardinality feedback? (Choose three.)
1z0-062 Exam QuestionsBrowse all questions from this exam
1z0-062 Exam - Question 70
Show AnswerHide Answer
Correct Answer: ACE
The optimizer automatically changes a plan during subsequent execution of a SQL statement if there is a huge difference in optimizer estimates and execution statistics. The optimizer enables monitoring for cardinality feedback after the first execution of a query to adjust the execution plan based on observed differences. After the optimizer identifies a query as a re-optimization candidate, statistics collected by the collectors are submitted to the optimizer for more accurate re-optimization.
Discussion
5 commentsRay520
Apr 7, 2022D is correct: cardinality feedback is called Statistics feedback in 12c. "In some cases, there are other techniques available to improve estimation; for instance, dynamic sampling or multi-column statistics allow the optimizer to more accurately estimate selectivity of conjunctive predicates. In cases where these techniques apply, statistics feedback is not enabled. However, if multi-column statistics are not present for the relevant combination of columns, the optimizer can fall back on statistics feedback." Reference: https://blogs.oracle.com/optimizer/post/statistics-feedback-formerly-cardinality-feedback
JMAN1
Jan 16, 2022I Think A C E. CF(cardinality feedback) is helping Dynamic sampling. In order to disable CF. You need to set _optimizer_use_feedback" to false at a session or statement level. So given answer D is wrong. E is correct.
JMAN1Options: ACE
Jan 16, 2022So given answer D is wrong. E is correct. A C E. Any comment please.
luizytoOptions: ACD
Jan 6, 2023In some cases, there are other techniques available to improve estimation; for instance, dynamic sampling or multi-column statistics allow the optimizer to more accurately estimate selectivity of conjunctive predicates. In cases where these techniques apply, statistics feedback is not enabled.
luizytoOptions: ACE
Jan 6, 2023In some cases, there are other techniques available to improve estimation; for instance, dynamic sampling or multi-column statistics allow the optimizer to more accurately estimate selectivity of conjunctive predicates. In cases where these techniques apply, statistics feedback is not enabled.