Oracle
1Z0-060 · Question #47
Examine the parameter for your database instance: You generated the execution plan for the following query in the plan table and noticed that the nested loop join was done. After actual execution of…
The correct answer is C. The optimizer used re-optimization cardinality feedback for the query. https://blogs.oracle.com/optimizer/entry/cardinality_feedback
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Question
Examine the parameter for your database instance:
You generated the execution plan for the following query in the plan table and noticed that the nested loop join was done. After actual execution of the query, you notice that the hash join was done in the execution plan:
Identify the reason why the optimizer chose different execution plans.
Exhibits
Options
- AThe optimizer used a dynamic plan for the query.
- BThe optimizer chose different plans because automatic dynamic sampling was enabled.
- CThe optimizer used re-optimization cardinality feedback for the query.
- DThe optimizer chose different plan because extended statistics were created for the columns used.
How the community answered
(37 responses)- A8% (3)
- B24% (9)
- C57% (21)
- D11% (4)
Explanation
https://blogs.oracle.com/optimizer/entry/cardinality_feedback
Topics
#adaptive query optimization#cardinality feedback#re-optimization#execution plan
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