Oracle OCP 1Z0-050（91-100题）解析
QUESTION 91:
Which statements are true regarding system-partitioned tables? (Choose all that apply.)
A. Only a single partitioning key column can be specified.
B. The same physical attributes must be specified for each partition.
C. Unique local indexes cannot be created on a system-partitioned table.
D. Traditional partition pruning and partition wise joins are not supported on these tables.
E. All DML statements must use partition-extended syntax.
Answer: C,D
解析：
参考Oracle官方文档：
https://docs.oracle.com/cd/E11882_01/appdev.112/e10765/dom_idx.htm#ADDCI4481
Supporting Operations with System-Partitioned Tables
The following operations continue to be supported by system partitioning:
Partition maintenance operations and other DDLs, with the exception of:
ALTER INDEX SPLIT PARTITION
ALTER TABLE SPLIT PARTITION
CREATE TABLE (as SELECT)
Creation of local indexes, with the exception of unique local indexes because they require a partitioning key
Creation of local bitmapped indexes
Creation of global indexes
All DML operations
INSERT AS SELECT operations with partition extended syntax, as shown in Example 8-19:
QUESTION 92:
ENCRYPT_TS is an encrypted tablespace that contains tables with data. Which statement is true regarding the effect of queries and data manipulation language (DML) statements on the encrypted data in the tables?
A. The data remains encrypted when it is stored in the redo logs.
B. The data remains encrypted when it is read into memory.
C. The data remains encrypted in the UNDO tablespace provided that the UNDO
tablespace was created with the encryption option enabled.
D. The data is decrypted during SORT and JOIN operations.
Answer: A
解析：
参考Oracle官方文档：
https://docs.oracle.com/cd/E11882_01/server.112/e40540/logical.htm#CNCPT402
https://docs.oracle.com/cd/E11882_01/server.112/e25494/tspaces.htm#ADMIN13316
Encrypted Tablespaces
You can encrypt any permanent tablespace to protect sensitive data. Tablespace encryption is completely transparent to your applications, so no application modification is necessary. Encrypted tablespaces primarily protect your data from unauthorized access by means other than through the database. For example, when encrypted tablespaces are written to backup media for travel from one Oracle database to another or for travel to an off-site facility for storage, they remain encrypted. Also, encrypted tablespaces protect data from users who try to circumvent the security features of the database and access database files directly through the operating system file system.
Tablespace encryption does not address all security issues. It does not, for example, provide access control from within the database. Any user who is granted privileges on objects stored in an encrypted tablespace can access those objects without providing any kind of additional password or key.
When you encrypt a tablespace, all tablespace blocks are encrypted. All segment types are supported for encryption, including tables, clusters, indexes, LOBs (BASICFILE and SECUREFILE), table and index partitions, and so on.
QUESTION 93:
You are managing an Oracle Database 11g ASM instance with a disk group dg01 having three disks. One of the disks in the disk group becomes unavailable because of power failure. You issued the following command to change the DISK_REPAIR_TIME
attribute from 3.6 hours to 5 hours:
ALTER DISKGROUP dg01 SET ATTRIBUTE 'disk_repair_time' = '5h';
To which disks in the disk group will the new value be applicable?
A. all disks in the disk group
B. all disks that are not currently in OFFLINE mode
C. all disks that are currently in OFFLINE mode
D. all disks in the disk group only if all of them are ONLINE
Answer: B
解析：
参考Oracle官方文档：
https://docs.oracle.com/cd/E11882_01/server.112/e10803/config_storage.htm#HABPT4813
4.4.5 Set the DISK_REPAIR_TIME Disk Group Attribute Appropriately
The DISK_REPAIR_TIME disk group attribute specifies how long a disk remains offline before Oracle ASM drops the disk. If a disk is made available before the DISK_REPAIR_TIME parameter has expired, the storage administrator can issue the ONLINE DISK command and Oracle ASM resynchronizes the stale data from the mirror side. In Oracle Database 11g, the online disk operation does not restart if there is a failure of the instance on which the disk is running. You must reissue the command manually to bring the disk online.
You can set a disk repair time attribute on your disk group to specify how long disks remain offline before being dropped. The appropriate setting for your environment depends on how long you expect a typical transient type of failure to persist.
Set the DISK_REPAIR_TIME disk group attribute to the maximum amount of time before a disk is definitely considered to be out of service.
QUESTION 94:
You have applications that have frequently executed queries, and produce small and static result sets.
You configure the sqlnet.ora file in the client machine to set a nonzero value for the OCI_RESULT_CACHE_MAX_SIZE parameter.
What is the purpose of this configuration?
A. to avoid round trips to the server by enabling caching of query results in client memory
B. to improve performance by storing a copy of the data from the private SQL area of the PGA
C. to enhance the query performance by creating a cache in the client memory for sorting operations
D. to avoid the storing of query plans and results in the server by creating a cache in the client memory
Answer: A
解析：
参考Oracle官方文档：
https://docs.oracle.com/cd/E11882_01/appdev.112/e10646/oci10new.htm#LNOCI16753
A client configuration file is optional and overrides the cache parameters set in the server init.ora initialization file. These parameters are part of a sqlnet.ora file. The following optional parameters are available for client configuration:
OCI_RESULT_CACHE_MAX_SIZE (optional) - Maximum size in bytes for the per-process query cache. Specifying a size less than 32768 in the client sqlnet.ora file disables the client result cache feature for client processes reading this sqlnet.ora file.
OCI_RESULT_CACHE_MAX_RSET_SIZE (optional) - Maximum size of any result set in bytes in the per-process query cache.
OCI_RESULT_CACHE_MAX_RSET_ROWS (optional) - Maximum size of any result set in rows in the per-process query cache.
Note that the cache lag cannot be set on the client.
QUESTION 95:
View the Exhibit to examine the parameter values.
You are planning to set the value for the MEMORY_TARGET parameter of your
database instance. What value would you assign?
A. 1440 MB
B. 90 MB
C. 362 MB
D. 272 MB
Answer: C
QUESTION 96:
You have the following requirements in relation to the detection of block corruption for your database instance:
1. Check for logical self-consistency of data blocks when modified in memory.
2. Checksums are calculated before and after the block change.
3. Checks are performed for the lost writes to the physical standby database.
Which method would help you perform the above checks automatically?
A. Set the DB_LOCK_CHECKSUM parameter to TYPICAL.
B. Set the DB_SECUREFILE parameter to PERMITTED.
C. Set the DB_LOST_WRITE_PROTECT parameter to TYPICAL.
D. Set the DB_ULTRA_SAFE parameter to DATA_ONLY.
Answer: D
QUESTION 97:
During the installation of Oracle Database 11g, you do not set ORACLE_BASE explicitly. You selected the option to create a database as part of the installation. How would this environment variable setting affect the installation?
A. The installation terminates with an error.
B. The installation proceeds with the default value but a message would be generated in the alert log file.
C. The installation proceeds with the default value but it would not be an OFA-compliant database.
D. The installation proceeds with the default value without warnings and errors.
Answer: B
Introduction to Oracle Base
The Oracle base location is the location where Oracle Database binaries are stored. During installation, you are prompted for the Oracle base path. Typically, an Oracle base path for the database is created during Oracle Grid Infrastructure installation.
To prepare for installation, Oracle recommends that you only set the ORACLE_BASE environment variable to define paths for Oracle binaries and configuration files. Oracle Universal Installer (OUI) creates other necessary paths and environment variables in accordance with the Optimal Flexible Architecture (OFA) rules for well-structured Oracle software environments.
For example, with Oracle Database 11g, Oracle recommends that you do not set an Oracle home environment variable allow OUI to create it instead. If the Oracle base path is /u01/app/oracle, then by default, OUI creates the following Oracle home path:
/u01/app/oracle/product/11.2.0/dbhome_1
Ensure that the paths you select for Oracle software, such as Oracle home paths and the Oracle base path, use only ASCII characters. Because installation owner names are used by default for some paths, this ASCII character restriction applies to user names, file names, and directory names.
https://docs.oracle.com/cd/E11882_01/em.112/e12255/oui2_manage_oracle_homes.htm#OUICG130
QUESTION 98:
You are managing an Oracle Database 11g database. You want to take the backup of MULT_DATA, a big file tablespace of size 100 TB on tape drive, but you have tape drives of only 10 GB each. Which method would accomplish the task quickly and efficiently?
A. parallel image copy backup
B. backup with MAXPIECESIZE configured for the channel
C. parallel backup with MAXPIECESIZE configured for the channel
D. intrafile parallel backup
Answer: D
QUESTION 99:
You perform the following activities during the database upgrade from Oracle Database 10g to Oracle Database 11g:
1. Capture plans for a SQL workload into a SQL Tuning Set (STS) before upgrade.
2. Load these plans from the STS into the SQL plan baseline immediately after the upgrade.
What is the reason for performing these activities?
A. to prevent plan capturing when the SQL statement is executed after the database
upgrade
B. to keep the plan in the plan history so that it can be used when the older version of the optimizer is used
C. to minimize plan regression due to the use of a new optimizer version
D. to completely avoid the use of new plans generated by a new optimizer version
Answer: C
QUESTION 100:
Which steps are mandatory to enable Direct NFS?
1. Mount all required file systems using the kernel NFS driver.
2. Create an oranfstab file containing the attributes for each NFS server to be accessed
using Direct NFS.
3. Replace the ODM library libodm11.so_stub with libodm11.so.
A. 2 and 3
B. 1 and 2
C. 1, 2 and 3
D. 1 and 3
Answer: D
解析：
Oracle直接NFS（DNFS）是一个优化的NFS（网络文件系统）客户端，它提供对NAS存储设备上的NFS存储的更快和更可扩展的访问（可通过TCP/IP访问）。直接NFS直接构建到数据库内核——就像ASM，主要用于使用DAS或SAN存储。
Oracle Direct NFS (dNFS) is an optimized NFS (Network File System) client that provides faster and more scalable access to NFS storage located on NAS storage devices (accessible over TCP/IP). Direct NFS is built directly into the database kernel - just like ASM which is mainly used when using DAS or SAN storage.
Direct NFS provides faster performance than what can be provided by the operating system's NFS driver as Oracle bypasses the operating system and generates exactly the requests it needs (no user configuration or tuning required). Data is cached just once in user space, which saves memory (no second copy in kernel space). Performance is further improved by load balancing across multiple network interfaces (if available).
Direct NFS is a new feature introduced with Oracle 11g.
Direct NFS is provided as part of the database kernel, and is thus available on all supported database platforms - even those that don't support NFS natively, like Windows.
Enabling Direct NFS
Execute these commands to enable Direct NFS:
cd $ORACLE_HOME/lib
mv libodm11.so libodm11.so_stub
ln -s libnfsodm11.so libodm11.so
Alternative way supported from 11.2 onward:
Enable
cd $ORACLE_HOME/rdbms/lib
make -f ins_rdbms.mk dnfs_on
Disable
cd $ORACLE_HOME/rdbms/lib
make -f ins_rdbms.mk dnfs_off
Configuration
Direct NFS uses a new configuration file (ORACLE_HOME/dbs/oranfstab) or the system's mount tab file (/etc/mtab) to find out what mount points are available.
Example oranfstab file:
server: MyNFSserver1
path: 192.168.1.1
path: 192.168.1.2
export: /vol/oradata1 mount: /mnt/oradata1