Oracle OCP 1Z0-050（171-180题）解析

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Oracle OCP 1Z0-050（171-180题）解析

QUESTION 171:

You are in the process of creating a virtual private catalog in your Oracle Database 11g database. The PROD1, PROD2, and PROD3 Oracle Database 10g databases are registered in the base recovery catalog. The database user who owns the base recovery catalog is CATOWNER. CATOWNER executes the following command to grant privileges to a new user VPC1 using Oracle Database 11g RMAN executables:

RMAN> GRANT CATALOG FOR DATABASE prod1, prod2 TO vpc1;

Then you issue the following commands:

RMAN> CONNECT CATALOG vpc1/oracle@catdb;

RMAN> SQL "EXEC catowner.dbms_rcvcat.create_virtual_catalog;"

What is the outcome of the above commands?

A. They produce an error because you need to connect as CATOWNER to execute this packaged procedure.

B. They execute and create a virtual catalog for pre-Oracle 11g clients.

C. They produce an error because PROD1 and PROD2 databases belong to the older version.

D. They produce an error because you need to connect to the target database to execute this packaged procedure.

Answer: B

解析：

以下是使用rman虚拟专用目录步骤：

1. 创建RMAN 基本目录：

RMAN> CONNECT CATALOG catowner/oracle@catdb

RMAN> CREATE CATALOG;

2. 将RECOVERY_CATALOG_OWNER授予给VPC 所有者：

SQL> CONNECT SYS/oracle@catdb AS SYSDBA

SQL> GRANT RECOVERY_CATALOG_OWNER to vpcowner;

3a.将REGISTER授予给VPC 所有者：

RMAN> CONNECT CATALOG catowner/oracle@catdb

RMAN> GRANT REGISTER DATABASE TO vpcowner;

3b.或将CATALOG FOR DATABASE授予给VPC 所有者：

RMAN>GRANT CATALOG FOR DATABASE db10g TO vpcowner;

4a.为11g客户机创建虚拟目录：

RMAN> CONNECT CATALOGvpcowner/oracle@catdb

RMAN> CREATE VIRTUAL CATALOG;

4b.或者为11g之前的客户机创建虚拟目录：

SQL> CONNECT vpcowner/oracle@catdb

SQL> exec catowner.dbms_rcvcat.create_virtual_catalog;

5. 在目录中注册新数据库：

RMAN> CONNECT TARGET / CATALOG vpcowner/oracle@catdb

RMAN> REGISTER DATABASE;

6. 使用虚拟目录：

RMAN> CONNECT TARGET / CATALOG vpcowner/oracle@catdb;

RMAN> BACKUP DATABASE;

可以为数据库组和用户组创建虚拟专用RMAN 目录。

1. 目录所有者将创建基本目录。

2. 目录数据库的DBA 可以创建拥有虚拟专用目录(VPC) 的用户，并授予其RECOVERY_CATALOG_OWNER权限。

3. 基本目录的所有者可为VPC 所有者授予访问先前注册的数据库的权限或授予REGISTER权限。GRANT CATALOG命令如下：

GRANT CATALOG FOR DATABASE prod1, prod2 TO vpcowner;

GRANT REGISTER命令如下：

GRANT REGISTER DATABASE TO vpcowner;

然后，虚拟目录所有者可连接到特定目标的目录，或者注册一个目标数据库。配置完VPC 之后，VPC 所有者可像使用标准基本目录一样使用该目录。

4. 创建虚拟专用目录。

a. 如果目标数据库是Oracle Database 11g数据库并且RMAN 客户机是11g客户机，则可使用RMAN 命令：

CREATE VIRTUAL CATALOG;

b. 如果目标数据库是Oracle Database 10g发行版2 或更早版本（使用兼容客户机），则必须从SQL*Plus 执行提供的过程：

BASE_CATALOG_OWNER.DBMS_RCVCAT.CREATE_VIRTUAL_CATALOG;

5. 使用VPC 所有者登录名连接到该目录，将其作为常规目录使用。

6. 虚拟目录所有者只能查看其有访问权限的那些数据库。对于大多数RMAN 操作，你还需要针对目标数据库的SYSDBA或SYSOPER权限。

 

QUESTION 172:

In which cases is reference partitioning effective in enhancing performance?

A. It is effective only in partition pruning.

B. It is effective in both partition pruning as well as partitionwise joins irrespective of whether the query predicates are different from or identical to the partitioning key.

C. It is effective in both partition pruning as well as partitionwise joins provided that the query predicates are identical to the partitioning key.

D. It is effective only in partitionwise joins provided that the query predicates are different from the partitioning key.

Answer: B

解析：

它在分区修剪以及智能化分区连接都是有效的，不论是否查询谓词（判断） 同分区键是不同或完全相同。

分区修剪，根据条件只访问对应的分区

http://docs.oracle.com/cd/E11882_01/server.112/e25555/tdpdw_perform.htm#TDPDW00821

 

Improving Performance: Partition Pruning

Partition pruning is an essential performance feature for data warehouses. In partition pruning, the optimizer analyzes FROM and WHERE clauses in SQL statements to eliminate unneeded partitions when building the partition access list. This enables Oracle Database to perform operations only on those partitions that are relevant to the SQL statement. Oracle Database prunes partitions when you use range, LIKE, equality, and IN-list predicates on the range or list partitioning columns, and when you use equality and IN-list predicates on the hash partitioning columns.

Partition pruning dramatically reduces the amount of data retrieved from disk and shortens the use of processing time, which improves query performance and resource use. If you partition the index and table on different columns (with a global partitioned index), partition pruning eliminates index partitions even when the partitions of the underlying table cannot be eliminated.

Depending upon the actual SQL statement, Oracle Database may use static or dynamic pruning. Static pruning occurs at compile time; the information about the partitions is accessed beforehand, dynamic pruning occurs at run time; the partitions are accessed by a statement and are not known beforehand. A sample scenario for static pruning is a SQL statement that contains a WHERE clause with a constant literal on the partition key column. An example of dynamic pruning is the use of operators or functions in the WHERE clause.

Partition pruning affects the statistics of the objects where pruning will occur and will affect the execution plan of a statement.

智能分区join，可以让对应的分区进行join

Improving Performance: Partitionwise Joins

Partitionwise joins reduce query response time by minimizing the amount of data exchanged among parallel execution servers when joins execute in parallel. This significantly reduces response time and improves the use of both CPU and memory resources. In Oracle Real Application Clusters environments, partitionwise joins also avoid or at least limit the data traffic over the interconnection, which is the key to achieving good scalability for massive join operations.

Partitionwise joins can be full or partial. Oracle Database decides which type of join to use.

QUESTION 173:

What recommendations does the SQL Access Advisor provide for optimizing SQL queries? (Choose all that apply.)

A. creation of bitmap, function-based, and B-tree indexes

B. creation of index-organized tables

C. optimization of materialized views for maximum query usage and fast refresh

D. selection of SQL plan baselines

E. partitioning of tables and indexes

Answer: A,C,E

解析：参考Oracle官方文档

http://docs.oracle.com/cd/E11882_01/server.112/e41573/advisor.htm#PFGRF95276

 

SQL Access Advisor index recommendations include bitmap, function-based, and B-tree indexes. A bitmap index offers a reduced response time for many types of ad hoc queries and reduced storage requirements compared to other indexing techniques. Bitmap indexes are most commonly used in a data warehouse to index unique or near-unique keys. SQL Access Advisor materialized view recommendations include fast refreshable and full refreshable MVs, for either general rewrite or exact text match rewrite.

SQL Access Advisor, using the TUNE_MVIEW procedure, also recommends how to optimize materialized views so that they can be fast refreshable and take advantage of general query rewrite.

Using SQL Access Advisor in Enterprise Manager or API, you can do the following:

• Recommend materialized views and indexes based on collected, user-supplied, or hypothetical workload information.
• Recommend partitioning of tables, indexes, and materialized views.
• Mark, update, and remove recommendations.

 

QUESTION 174:

You are managing an Oracle 11g database with ASM storage, for which the COMPATIBLE initialization parameter is set to 11.1.0. In the ASM instance, the COMPATIBLE.RDBMS attribute for the disk group is set to 10.2 and the COMPATIBLE.ASM attribute is set to 11.1.

Which two statements are true in this scenario for the features enabled for ASM? (Choose two.)

A. The ASM supports variable sizes for extents of 1, 8, and 64 allocation units.

B. The ASM-preferred mirror read feature is enabled.

C. The RDBMS always reads the primary copy of a mirrored extent of the ASM disk group.

D. The ASM disk is dropped immediately from a disk group when it becomes unavailable.

Answer: A,B

解析：

您用ASM存储管理Oracle 11g数据库，可兼容的初始化参数设置为11.1.0。在ASM实例中，用于磁盘组的COMPATIBLE.RDBMS属性设置为10.2并且COMPATIBLE.ASM属性设置为11.1。

为ASM启用的特性，在此方案中哪两项描述是真实的？

A. ASM首选镜像读取功能被启用。

B. ASM支持用于1个、 8个和64个分配单元的区的可变大小。

 

QUESTION 175:

You want to take the backup of the USERS tablespace. It has a single data file of 900 MB.. You have tape drives of 300 MB each. The SBT channel is configured for the RMAN. To accomplish the backup, you issued the following RMAN command:

RMAN> BACKUP SECTION SIZE 300M TABLESPACE users;

Which two statements are true regarding the execution of the above command? (Choose two.)

A. The RMAN parallelizes the backup although the parallelism is not set for a channel.

B. The backup piece size will be limited to 300 MB.

C. The operation is accomplished using the default channel available.

D. Three channels for the tape drive must be configured by setting the parallelism to three.

Answer: B,C

解析：参考Oracle官方文档

http://docs.oracle.com/cd/E11882_01/backup.112/e10643/rcmsynta007.htm#RCMRF90025

A,错误，如果没有设置并行度，那么备份时只能只用默认的configure里面配置的并行度执行，但是默认并行度为1，即只能通过一个通道来备份，并不是并行备份的。

B：正确，指定每个备份的大小为300M，所以每个备份片被限制为300M

C：正确，使用默认的可用的通道来完成备份，正确的。

D：错误，不是一定，只是，多配置几个通道，速度会更快点，但不是一定要配置3个，使用默认的一个通道也可以备份的。

 

QUESTION 176:

Exhibit #1:

Exhibit #2:

View the Exhibit exhibit1 to observe the maintenance window property.

View the Exhibit exhibit2 to examine the output of the query.

Which two statements describe the conclusions? (Choose two.)

A. RESOURCE_PERCENTAGE should be increased.

B. The repeat time for the window should be decreased.

C. RESOURCE_PERCENTAGE should be decreased.

D. The window duration should be increased.

Answer: A,D

解析：

图1，观察维护窗口属性；图2查询的输出
 (Choose two.)哪两句描述结论？
A. RESOURCE_PERCENTAGEshould be increased.资源百分比应该增加
D. The window durationshould be increased.窗口期限应该增加

QUESTION 177:

Exhibit:

View the Exhibit to examine the error obtained during the I/O calibration process.

There are no data files on raw devices. What is the reason for this error?

A. Another session runs the I/O calibration process concurrently.

B. The FILESYSTEMIO_OPTIONS parameter is set to NONE.

C. The pending area has not been created before running the I/O calibration process.

D. The DISK_ASYNCH_IO parameter is set to TRUE.

Answer: B

解析：参考Oracle官方文档

http://docs.oracle.com/cd/E11882_01/server.112/e41573/os.htm#PFGRF94412

查看图表检查在I/ O校准过程中得到的错误。在裸设备上没有数据文件。此错误的原因是什么？

You can use the FILESYSTEMIO_OPTIONS initialization parameter to enable or disable asynchronous I/O or direct I/O on file system files. This parameter is platform-specific and has a default value that is best for a particular platform.

FILESYTEMIO_OPTIONS can be set to one of the following values:

• ASYNCH: enable asynchronous I/O on file system files, which has no timing requirement for transmission.
• DIRECTIO: enable direct I/O on file system files, which bypasses the buffer cache.
• SETALL: enable both asynchronous and direct I/O on file system files.
• NONE: disable both asynchronous and direct I/O on file system files.

 

QUESTION 178:

Which statement is true for enabling Enterprise Manager Support Workbench in Oracle Database 11g to upload the physical files generated by Incident Packaging Service (IPS) to MetaLink?

A. The path for the Automatic Diagnostic Repository (ADR) must be configured with the DIAGNOSTIC_DEST initialization parameter.

B. Select the Enable option in the Oracle Configuration Manager Registration window during the installation of the Oracle Database 11g software, provide valid MetaLink credentials and select license agreement.

C. The Enterprise Manager Support Workbench can be enabled only if the background process manageability monitor (MMON) is configured.

D. No special setup is required, and the feature is enabled by default.

E. The database must be running in ARCHIVELOG mode.

Answer: B

解析：

http://docs.oracle.com/cd/E11882_01/server.112/e25494/diag.htm#ADMIN12303

About Incident Packages

For the customized approach to uploading diagnostic data to Oracle Support, you first collect the data into an intermediate logical structure called an incident package (package). A package is a collection of metadata that is stored in the Automatic Diagnostic Repository (ADR) and that points to diagnostic data files and other files both in and out of the ADR. When you create a package, you select one or more problems to add to the package. The Support Workbench then automatically adds to the package the problem information, incident information, and diagnostic data (such as trace files and dumps) associated with the selected problems. Because a problem can have many incidents (many occurrences of the same problem), by default only the first three and last three incidents for each problem are added to the package, excluding any incidents that are over 90 days old. You can change these default numbers on the Incident Packaging Configuration page of the Support Workbench.

After the package is created, you can add any type of external file to the package, remove selected files from the package, or edit selected files in the package to remove sensitive data. As you add and remove package contents, only the package metadata is modified.

When you are ready to upload the diagnostic data to Oracle Support, you first create a zip file that contains all the files referenced by the package metadata. You then upload the zip file through Oracle Configuration Manager.

QUESTION 179:

Which statements are true regarding SecureFile LOBs? (Choose all that apply.)

A. The amount of undo retained is user controlled.

B. It automatically detects duplicate LOB data and conserves space by storing only one copy.

C. SecureFile encryption allows for random reads and writes of the encrypted data.

D. Fragmentation is minimized by using variable-sized chunks dynamically.

E. SecureFile LOBs can be used only for nonpartitioned tables.

Answer: C,D

解析：

Oracle Database 11g 将LOB 数据类型作为Oracle SecureFiles进行了完全重新设计，显著改进了应用程序开发的性能、可管理性和易用性。

使用SecureFiles时，块大小介于Oracle数据块大小到64 MB 之间。Oracle DB 尝试使数据集中在磁盘的相邻物理位置，从而将内部碎片降到最低。通过使用可变的块大小，SecureFiles避免对不必要的大型LOB 数据块进行版本化。

SecureFiles还提供了新的客户机/服务器网络层，从而允许在支持更高读写性能的服务器和客户机之间进行高速数据传输。SecureFiles自动确定生成重做和还原的最有效方法，因而不需要用户定义参数。SecureFiles自动确定是仅为更改生成重做和还原，还是通过生成完整的重做记录创建新版本。

由于SecureFiles需要维护各种内存中统计信息以帮助有效地分配内存和空间，所以将其设计为可自适应的智能工具。这样，由于减少了很难使用不可预测的负荷进行优化的可优化参数数量，可管理性有所提高。

SecureFiles：高级功能

Oracle SecureFiles实施也提供了下一代高级功能，如智能压缩和透明加密。压缩功能支持显式压缩SecureFiles 。SecureFiles仅为随机读取或写入访问透明解压缩所需的数据块集，从而自动维护未压缩和已压缩的偏移量之间的映射。如果将压缩级别从MEDIUM 更改为HIGH，则映射会自动进行更新以反映新的压缩算法。取消重复可自动检测重复的SecureFile LOB数据，并通过仅存储一个副本来节省空间-减少磁盘存储空间、I/O和重做事件记录。可在表级别或分区级别指定取消重复，但不能跨越分区的LOB。取消重复需要使用高级压缩选项。

现在可以在适当位置存储加密的LOB数据，并对其进行随机读取和写入，因而提高了数据的安全性。只能按列加密SecureFile LOB（与透明数据加密相）。将使用相同的加密算法对LOB列中的所有分区进行加密。无法对BasicFiles 数据进行加密。SecureFiles支持行业标准加密算法：3DES168 、AES128、AES192（默认）和AES256。加密是高级安全选项的一部分。

注：必须将COMPATIBLE初始化参数设置为11.0.0.0.0 或更高，才能使用SecureFiles 。在11.1.0.0.0 兼容性下BasicFiles（以前的LOB）格式仍然受支持。设置11.0.0.0.0 后不会出现功能降低。

QUESTION 180:

You executed the following commands in an RMAN session for your database instance that has failures:

RMAN> LIST FAILURE;

After some time, you executed the following command in the same session:

RMAN> ADVISE FAILURE;

But there are new failures recorded in the Automatic Diagnostic Repository (ADR) after the execution of the last LIST FAILURE command. Which statement is true for the above ADVISE FAILURE command in this scenario?

A. It produces advice only for new failures and the failures listed in the last LIST FAILURE command are ignored.

B. It produces a warning for new failures before advising for CRITICAL and HIGH failures.

C. It produces an error with recommendation to run the LIST FAILURE command before the ADVISE FAILURE command.

D. It ignores new failures and considers the failures listed in the last LIST FAILURE command only.

Answer: B

解析：参考Oracle官方文档

http://docs.oracle.com/cd/E11882_01/backup.112/e10643/rcmsynta003.htm#RCMRF166

If a new failure has been recorded in the diagnostic repository since the last LIST FAILURE command in the current RMAN session, then RMAN issues a warning before advising on CRITICAL and HIGH failures.