ocp-v13-480

来源：互联网发布：阿里云怎么添加监控编辑：程序博客网时间：2024/04/29 17:13

QUESTION 480
View the Exhibit exhibit1 to examine the series of SQL commands.
View the Exhibit exhibit2 to examine the plans available in the SQL plan baseline. The baseline in the first
row of the Exhibit is created when OPTIMIZER_MODE was set to FIRST_ROWS.
Which statement is true if the SQL query in exhibit1 is executed again when the value of
OPTIMIZER_MODE is set to FIRST_ROWS?

这里写图片描述

A. The optimizer uses a new plan because none of the plans in the exhibit2 are fixed plans.
B. The optimizer uses the plan in the second row of the exhibit2 because it is an accepted plan.
C. The optimizer uses the plan in the first row of the exhibit2 because it is the latest generated plan.
D. The optimizer uses the plan in the first row of the exhibit2 because OPTIMIZER_MODE was set to
FIRST_ROW during its creation.
Correct Answer: B

查看展图1 检查SQL命令序列

查看图2 检查SQL计划基线可用计划

这里写图片描述
当OPTIMIZER_MODE设置成FIRST_ROWS时，在第一行中的基线创建。
当OPTIMIZER_MODE的值设置成FIRST_ROWS时，如果图1中的SQL查询再执行一遍那么哪一句是正确的

B.因为这是个已经被接受的计划，所以优化器使用了在图2中的第二行的计划

答案是 B

0 1