【CUUG内部资料】OCP-12C-1Z0-062题库解析-第4次课
【CUUG内部资料】OCP讨论群：1015267481【CUUG内部资料】OCP-12C-1Z0-062题库解析-第1次课序：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QUESTION 46Which three features work together, to allow a SQL statement to have different cursors for thesame statement based on different selectivity ranges?A. Bind Variable PeekingB. SQL Plan BaselinesC. Adaptive Cursor SharingD. Bind variable used in a SQL statementE. Literals in a SQL statementCorrect Answer: ACESection: (none)ExplanationExplanation/Reference:（如果优化器能知道文本变量的值，更容易产生更加优秀的执行计划，这意味着使用文本变量更容易产生好的执行计划，而非绑定变量。当你执行一个 SQL 的时，如果你使用了绑定变量，这将意味着变量的值对优化器是未知的，优化器只能把它当做一个普通值处理。产生的执行计划就可能不够符合值的特征。使用了字符常量后，优化器知道如何根据直方图信息生成优秀的执行计划，那么使用绑定变量会变成什么样呢？这个依赖于 ORACLE 的版本。在 ORACLE 9i/10g 版本，ORACLE 会在第一次硬解析的时候，窥探绑定变量的值，然后生成执行计划，后面的 SQL 都会使用这个执行计划来执行。（引发了很多问题）在 ORACLE 11g 版本，ORACLE 有一个 adaptive cursor sharing 的特性，根据不同的绑定值可能产生不同的执行计划，可以解决 9i/10g 的问题。）QUESTION 47You notice a performance change in your production Oracle 12c database. You want to knowwhich change caused this performance difference.Which method or feature should you use?A. Compare Period ADDM reportB. AWR Compare Period reportC. Active Session History (ASH) reportD. Taking a new snapshot and comparing it with a preserved snapshotCorrect Answer: B（解析：比较数据库不同时间段的性能差异，最好的方法就是比较 AWR 报告）QUESTION 48You want to capture column group usage and gather extended statistics for better cardinalityestimates for the CUSTOMERS table in the SH schema.Examine the following steps:1. Issue the SELECT DBMS_STATS.CREATE_EXTENDED_STATS (SH', CUSTOMERS')FROM dual statement.2. Execute the DBMS_STATS.SEED_COL_USAGE (null, SH', 500) procedure.3. Execute the required queries on t he CUSTOMERS table.4. Issue the SELECT DBMS_STATS.REPORT_COL_USAGE (SH', CUSTOMERS') FROMdual statement.Identify the correct sequence of steps.A. 3, 2, 1, 4B. 2, 3, 4, 1C. 4, 1, 3, 2D. 3, 2, 4, 1Correct Answer: BSection: (none)ExplanationExplanation/Reference:Step 1 (2). Seed column usageOracle must observe a representative workload, in order to determine the appropriate columngroups. Using the new procedureDBMS_STATS.SEED_COL_USAGE, you tell Oracle how long it should observe the workload.Step 2: (3) You don't need to execute all of the queries in your work during this window. You cansimply run explain plan for some of your longer running queries toensure column group information is recorded for these queries.Step 3. (1) Create the column groupsAt this point you can get Oracle to automatically create the column groups for each of t he tablesbased on the usage information captured during the monitoringwindow. You simply have to call t he DBMS_STATS.CREATE_EXTENDED_STATS function foreach table.This function requires just two arguments, the schemaname and the table name. From then on, statistics will be maintained for each column groupwhenever statistics are gathered on the table.QUESTION 49Which three statements are true about Automatic Workload Repository (AWR)?A. All AWR tables belong to the SYSTEM schema.B. The AWR data is stored in memory and in t he database.C. The snapshots collected by AWR are used by the self-tuning components in t he databaseD. AWR computes time model statistics based on time usage for activities, which are displayedin t he v$SYS time model and V$SESS_TIME_MODEL views.E. AWR contains system wide tracing and logging information.Correct Answer: BCD( 解析：工作负载存储库的一个基本方面是，它以支持历史性能分析的方式收集和保存数据库性能数据。其机制是 awr 快照。在周期性的基础上，awr 获取存储在数据库实例内存中的当前统计值的“快照”，并将它们保存到位于sysaux 表空间中的表中。*awr 主要是为高级组件（如自动调优算法和顾问）提供输入，但也可以为手动调优过程提供丰富的信息。AWR 表属于sysman 用户；答案 E 是属于 ADR（adrci）功能。时间模型的统计是 AWR 中很重要的一个功能。）QUESTION 50You upgraded your database from pre-12c to a multitenant container database (CDB) containingpluggable databases (PDBs).Examine the query and its output:Which two tasks must you perform to add users with SYSBACKUP, SYSDG, and SYSKMprivilege to the password file?A. Assign the appropriate operating system groups to SYSBACKUP, SYSDG, SYSKM.B. Grant SYSBACKUP, SYSDG, and SYSKM privileges to the intended users.C. Re-create the password file with SYSBACKUP, SYSDG, and SYSKM privilege and theFORCE argument set to No.D. Re-create the password file with SYSBACKUP, SYSDG, and SYSKM privilege, and FORCEarguments set to Yes.E. Re-create the password file in t he Oracle Database 12c format.Correct Answer: BD（解析： Administrative PrivilegesAdministrative privileges that are required for an administrator to perform basicdatabase operations are granted through the following special system privileges: SYSDBA SYSOPER SYSBACKUP SYSDG SYSKM您必须拥有其中一个授予您的特权，这取决于您需要的授权级别。从 Oracle 数据库 12c 开始，可以使用 SysBackup、SysDG 和 SysKM 管理权限。每个新的管理权限都授予完成每个管理领域任务所需的最低权限。新的管理权限使您能够避免授予 sysdba 管理权限对于许多常见的任务。查询使用密码文件是用户：SQL> select * from v$pwfile
