第101题-OCP认证062考试题库2019最新考题解析
最新学讯：近期OCP认证正在报名中，因考试人员较多请尽快报名获取最近考试时间，报名费用请联系在线老师，甲骨文官方认证，报名从速！
我要咨询2018年的时候，OCP 11g考试题库大更新，052 053出现了很多新题，
2019年，11g即将停考的前期，Oracle又出现了一次大变动，12c出现了很多新题，比如062 063题库大更新
OCP解析公开课时间：【每周五晚8点】
OCP解析公开课地址：http://ke.qq.com/course/326223
OCP解析群资料分享：1015267481 验证：ocp
-------------------------------------------------------
QUESTION 101
Examine the parameters for your database instance:
optimizer_adaptive_reporting_only boolean FALSE
optimizer_adaptive_statistics boolean FALSE
optimizer_capture_sql_plan_baselines boolean FALSE
optimizer_dynamic_sampling integer 2
optimizer_features_enable string 12.1.0.1
Which three statements are true about the process of automatic optimization by using cardinality feeDBAck?
A. 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.
B. The optimizer can re optimize a query only once using cardinality feeDBAck.
C. The optimizer enables monitoring for cardinality feeDBAck after t he first execution of a query.
D. The optimizer does not monitor cardinality feeDBAck if dynamic sampling and multicolumn statistics are enabled.
E. After the optimizer identifies a query as a re-optimization candidate, statistics collected by the collectors are submitted to the optimizer.
Correct Answer: ACD
Section: (none)
( 解析： 在下列情况 CBO 可能无法估算出准确的 Cardinality，Oracle 会启用 CFB 功能：
?没有收集表的统计信息，并且 dynamic sampling 也没有开启;
? 一个表的查询条件涉及多列，但却没有收集扩展的统计信息(extended statistics)
? 查询条件复杂(比如条件有函数)
