Oracle OCP认证考试IZ0-053题库共712题数据库（带中文解析）

部分题如下：

1.Whiledeploying a new application module, the software vendor ships the applicationsoftware alongwithappropriate SQL plan baselines for the new SQLs being introduced. Which two statementsdescribetheconsequences? (Choose two.)A. The planbaselines can be evolved over time to produce better performance.B. Thenewly generated plans are directly placed into the SQL plan baseline withoutbeing verified.C. The newSQL statements initially run with the plans that are known to produce goodperformanceunderstandard test configuration.D. Theoptimizer does not generate new plans for the SQL statements for which the SQLplan baselinehas beenimported.
Answer: AC答案解析：参考当部署一个新的应用模块时，软件供应商与用于被引入的新SQL的适当的SQL计划基线一起运送应用软件。哪两个语句描述了后果？ A, 计划基线可以随着时间的推移演变，产生更好的性能。C,新的SQL语句最初与计划一起运行，该计划在标准测试配置下已知能产生良好的性能。 新应用程序部署：部署新的应用程序模块意味着在系统中引入新的 SQL 语句。软件供应商可以将应用程序软件与新引入的SQL语句的相应SQL 计划基线一起提供。由于存在计划基线，新的SQL 语句最初将与已知在标准测试配置下具有良好性能的计划一起运行。但是，如果客户系统配置与测试配置有很大的差异，则计划基线可随时间演化以产生更好的性能。
2.You planto have a larger moving window size for the default system-defined moving windowbaselinebecause youwant to use the adaptive threshold.Whichstatement factors in this consideration while increasing the size of the movingwindow.?A. Thecollection level for the AWR should be set to BASIC.B. Themoving window size must be less than Undo Retention.C. Themoving window size should be greater than the Automatic Workload Repository(AWR) retention period.D. Themoving window size should be equal to or less than the Automatic WorkloadRepository (AWR) retention period.
Answer: D
答案解析：参考 1936
[font="]Moving Window BaselineA moving window baseline corresponds toall AWR data that exists within the AWR retention period. This is usefulwhen using adaptive thresholds because the database can use AWR data inthe entire AWR retention period to compute metric threshold values.Oracle Database automatically maintainsa system-defined moving window baseline. The default window size for thesystem-defined moving window baseline is the current AWR retentionperiod, which by default is 8 days. If you are planning to useadaptive thresholds, consider using a larger moving window—such as 30 days—toaccurately compute threshold values. You can resize the moving window baselineby changing the number of days in the moving window to a value that is equal to orless than the number of days in the AWR retention period. Therefore,to increase the size of a moving window, you must first increase the AWRretention period accordingly.
参考
移动窗口基线Oracle Database 会自动维护一个系统定义的移动窗口基线。系统定义的移动窗口基线的默认窗口大小为当前的AWR 保留期（默认为八天）。如果计划使用自适应阈值，则可考虑使用较大的移动窗口（如30 天），以便精确地计算阈值。通过将移动窗口中的天数更改为等于或小于AWR 保留期中的天数的值，可以调整移动窗口基线的大小。因此，要增加移动窗口的大小，需要先相应地增加AWR 保留期。这种系统定义的基线提供了一个现成的默认基线，EM 的性能屏幕可对照当前的数据库性能对性能进行比较。注：在OracleDatabase 11g中，快照数据的默认保留期已经从七天更改为八天，以确保捕获整周的性能数据。