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ocp 043 1-50

原创 Linux操作系统 作者:甲骨文-MarkChen 时间:2012-04-18 22:15:00 0 删除 编辑

1. You need to check the EMP_EAST partition in the EMPLOYEES table for physical corruptions. You also need to verify that the rows belong to the correct partition. Which option could you use?

A.LogMiner

B.the DBNEWID utility

C.the DBVERIFY utility

D.the ANALYZE command

E.the RMAN REPORT command

F.the RMAN CROSSCHECK command

G.the RMAN BLOCKRECOVER command

答案:D

解析:

DBVERIFY:是一种外部命令行实用程序,可以对脱机或联机的数据库执行物理数据结构完整性检查。可以对备份文件与联机文件(或文件片段)运行此实用程序。只能检查数据文件;不能检查重做日志文件

ANALYZE:使用 ANALYZE 命令可以验证表或表分区的结构,以及索引或索引分区的结构。

要分析的对象必须位于本地计算机,并且必须是在您自己的方案中,或者必须拥有ANALYZEANY 系统权限。CASCADE 选项可以验证对象,包括该对象的所有相关对象。不将块标记为软损坏;只报告软损坏情况

RMAN CROSSCHECK:当手工删除了归档日志以后,Rman 备份会检测到日志缺失,从而无法进一步继续执行。所以此时需要手工执行crosscheck 过程,之后Rman 备份可以恢复正常。

根据题意验证分区表的block,验证行是否属于正确的分区,所以要选ANALYZE



2. You execute the following command to enable a session in resumable mode:

SQL> ALTER SESSION ENABLE RESUMABLE TIMEOUT 60;

What is the impact of a timeout on the statements being suspended?

A.The statements remain suspended for at least 60 seconds.

B.The statements are suspended for 60 seconds and then they are executed.

C.The suspended statements error out if the problem is not rectified within 60 seconds.

D.The statements are automatically suspended 60 seconds after an error is received, and then attempt toexecute normally again.

答案:C

解析:Oracle 提供了一种 方法,当对数据库执行操作时,出现分配存储空间失败的错误时,Oracle 不是简单的返回错误信息,并回滚整个事务,而是将执行的语句置于悬挂状态,等待一段时间,在等待时间内,如果问题得到解决,则语句会继续执行下去,如果问题一直无法解决,则会报错并回滚。产生SUSPEND 的前提是当前的session 处于ENABLE RESUMABLE 状态。而且发出的语句遇到下面三种错误:空闲空间不足、达到最大的MAXEXTENTS 和达到用户的空间QUOTA 限制。

C 选项,如果在60s 内没有解决问题,挂起状态将报错。按理说A 选项也应该是对的,就是说挂起状态会保留至少60s,不知道是不是至少出的错.



3. Immediately after adding a new disk to or removing an existing disk from an Automatic StorageManagement (ASM) instance, you find that the performance of the database decreases initially, until the

addition or removal process is completed. Performance then gradually returns to normal levels.

Which two activities could you perform. to maintain a consistent performance of the database while adding or removing disks? (Choose two.)

A.increase the number of checkpoint processes

B.define the POWER option while adding or removing the disks

C.increase the number of DBWR processes by setting up a higher value for DB_WRITER_PROCESSES

D.increase the number of slave database writer processes by setting up a higher value for DBWR_IO_SLAVES

E.increase the number of ASM Rebalance processes by setting up a higher value for ASM_POWER_LIMIT during the disk addition or removal process

答案:BE

解析:

在ASM 实例添加和删除磁盘,在没有完之前数据库会很慢,用什么方法可以在不影响数据库

速度的情况下添加或删除磁盘

Striping:条带化

条带化是把连续的数据分割成相同大小的数据块,把每段数据分别写入到阵列中不同磁盘上的方法。此技术非常有用,它比单个磁盘所能提供的读写速度要快的多,当数据从第一个磁盘上传输完后,第二个磁盘就能确定下一段数据。数据条带化正在一些现代数据库和某

些RAID 硬件设备中得到广泛应用。

ASM_POWER_LIMIT:该参数控制重新平衡操作的速度。值的范围在1 到 11 之间,11 表示速度最快。如果省略,该值将默认为 1。从属进程的数量可以从手动重新平衡命令 (POWER)中指定的并行级别派生,或者通过 ASM_POWER_LIMIT 参数派生。

ALTER DISKGROUP dg1 add disk ‘ddd’ REBALANCE POWER 5;

最小值0 代表不做Rebalance

最大值11 代表最快的速度,也意味最严重的性能影响

1 代表最慢的速度和最小的性能影响

重新平衡不会妨碍任何数据库操作。重新平衡进程主要会对系统上的 I/O 负载产生影响。

重新平衡的强度越高,它加在系统上的 I/O 负载也就越大。这样,可供数据库I/O 使用的

I/O 带宽就越少。

如果 ASM 环境是使用命令行而不是通过EM 创建的,则必须先创建磁盘组然后才能装

载。



4. You enabled Automatic Shared Memory Management. The initialization parameters are set as shown below:

SGA_TARGET = 10GB

SGA_MAX_SIZE = 14GB

STREAMS_POOL_SIZE = 1GB

SHARED_POOL_SIZE = 3GB

Which two statements are correct in this scenario? (Choose two.)

A.A maximum of 3 GB can be allocated to shared pool.

B.The value for SGA_TARGET can be increased up to a maximum of 14 GB.

C.A total of 14 GB memory will be allocated to the automatically tuned memory components.

D.Increasing the value for SGA_TARGET will automatically increase the memory allocated for STREAMS_POOL_SIZE.

E.Increasing the value for SGA_TARGET to 12 GB will automatically increase the memory allocated to autotuned parameters.

F.Reducing the value for SGA_TARGET to 9 GB will automatically decrease the memory allocated to shared pool from 3 GB to 2 GB.

答案:BE

解析:SHARED_POOL_SIZE 设置值后只会增加,不会减少



5. Manually, you set the consumer group of all of the newly created users to MYDB_GRP. You want the users to be able to change their consumer groups as per the application requirement.

What was the first step that was needed in the process to achieve this objective?

A.The user must have been granted the DBA role.

B.The user must have been granted the switch privilege as a part of a role.

C.The user must have been granted the Resource Manager administrator privilege.

D.The user must have been granted the switch privilege by using the DBMS_RESOURCE_MANAGER_PRIVS package.

答案:D

解析:

资源管理概述:

资源管理器有三个部件组成:

资源用户组(Resource consumer group )

资源规划(Resource plan )

资源分配方法(Resource allocation method)

资源计划目录(Resource plan directives)

它们的功能如下:

资源用户组: 根据数据库资源处理需求,将用户会话分成组资源规划: 指定哪些资源分配给资源用户的命令资源分配方法: 数据库资源管理器分配特殊资源时采用的方法,由资源用户组和资源规划来使用。

资源规划命令: 管理员使用这些命令将资源用户组与特殊规划连接起来,并在资源用户组之间分配资源。

数据库资源管理器可以完成:

.确保某些用户处理少量的资源,不考虑对系统的加载和用户的数量。
.按比例将CPU时间分配给不同的用户和程序,分配有效的处理资源。
.限制一组用户可以使用的并行度。
.对实例进行配置,使其能使用特殊的资源分配方法。例如,DBA不用关闭数据库实例就可以动态地改变这些配置方法。

授予用户“切换权限”:
BEGIN
//撤消用户
dbms_resource_manager_privs.revoke_switch_consumer_group('JOSEN', 'SDL');
//添加用户并授于切换特权选项
dbms_resource_manager_privs.grant_switch_consumer_group('JOSEN', 'SDL', true);
END;



6. You have set the value of the NLS_TIMESTAMP_TZ_FORMAT parameter in the parameter file to

YYYY-MM-DD. The default format of which two data types would be affected by this setting? (Choose two.)

A.DATE

B.TIMESTAMP

C.INTERVAL YEAR TO MONTH

D.INTERVAL DAY TO SECOND

E.TIMESTAMP WITH LOCAL TIME ZONE

答案:BE

解析:NLS_TIMESTAMP_TZ_FORMAT defines the default timestamp with time zone format to use with the TO_CHAR and TO_TIMESTAMP_TZ functions



7. You executed the following command in Recovery Manager (RMAN) to perform. a backup of the DETTBS tablespace:

RMAN> BACKUP TABLESPACE DETTBS;

Under which conditions would this command execute successfully? (Choose all that apply.)

A.The database is in NOMOUNT state.

B.The database is in ARCHIVELOG mode and the tablespace is online.

C.The database is in ARCHIVELOG mode and the tablespace is offline.

D.The database is in NOARCHIVELOG mode and the tablespace is online.

E.The database is in NOARCHIVELOG mode and the tablespace is offline.

答案:BCE

解析:

在NOARCHIVELOG 下,只能备份read only 及offline 的表空间

RMAN> backup tablespace users;

启动 backup 于 17-3 月 -11

使用通道 ORA_DISK_1

通道 ORA_DISK_1: 启动全部数据文件备份集

通道 ORA_DISK_1: 正在指定备份集中的数据文件

RMAN-03009: backup 命令 (ORA_DISK_1 通道上, 在 03/17/2011 14:05:13 上)

失败

ORA-19602: 无法按 NOARCHIVELOG 模式备份或复制活动文件



8. You lost a temporary file that belongs to the default temporary tablespace in your database. From the options provided, which approach would you take to solve the problem?

A.flash back the database

B.import the temporary tablespace from the last export

C.restore all the data files and temporary files from the last full database backup and perform. a recovery

D.not perform. a recovery, but create a new temporary tablespace, make it the default temporary tablespace and then drop the old tablespace

答案:D

解析:你的临时数据文件丢失了(属于临时表空间),这时不用去闪回或者回复,直接删除原来的旧有临时表空间,新建一个新的就行了。

创建临时表空间
create temporary tablespace TEMP1 TEMPFILE 'E:ORACLEORADATAORCL9temp02.DBF' SIZE 512M REUSE AUTOEXTEND ON NEXT 1M MAXSIZE UNLIMITED;

改变缺省临时表空间 为刚刚创建的新临时表空间temp1
alter database default temporary tablespace temp1;

删除原来临时表空间
drop tablespace temp including contents and datafiles;



9. You executed the following command in Recovery Manager (RMAN):

RMAN> RESTORE CONTROLFILE;

Which operation must you perform. before this command is executed?

A.back up the control file to trace

B.bring database to the MOUNT state

C.open a connection to the RMAN recovery catalog, which contains the RMAN metadata for the target database

D.set the database ID (DBID), but only if the DB_NAME parameter associated with the target database is unique in the recovery catalog

答案:C

解析:

1.使用增量备份只能用rman 在catalog 情况下,从nomount 就可以恢复

2.如果不看备份脚本,目前从备份文件或是catalog 信息无法判断是差异增量还是累计增量的

3. rman>create script. sc1{

delete noprompt backup;

backup as compressed backupset full database;

backup archivelog all;}

只有catalog 下情况用rman>list script. names;

1 个catalog 可以对多库(至于库名 DB_NAME 是否唯一需实验)

rman>run{execute sript sc1}; 可以写成批处理里面

rman>delet copy;



10. You are using Oracle Database 10g. You performed an incomplete recovery of your database and opened the database with the RESETLOGS option.

What is the effect of opening the database with the RESETLOGS option? (Choose two.)

A.This operation resets the SCN for the database.

B.This operation creates a new incarnation of the database.

C.This operation moves all the redo log files to a different location.

D.This operation deletes the old redo log files and creates new redo log files.

E.This operation updates all current datafiles and online redo logs and all subsequent archived redo logs with a new RESETLOGS SCN and time stamp.

答案:BE

解析:

select file#,checkpoint_change# from v$datafile;

select file#,checkpoint_change# from v$datafile_header;

只要以上两个不一致,就需要resetlog 打开

alter database open resetlogs; 即截断多余的scn , resetscn 更好

a.截断scn (有疑问) (warehous)

b.把当前日志归档

c.序列号从1 开始了 重建日志了

http://blog.csdn.net/leishifei/article/details/6430057



11. These are the details about V$FLASHBACK_DATABASE_STAT:

SQL> DESC V$FLASHBACK_DATABASE_STAT

Name Null? Type

------------- -------- --------------

BEGIN_TIME DATE

END_TIME DATE

FLASHBACK_DATA NUMBER

DB_DATA NUMBER

REDO_DATA NUMBER

ESTIMATED_FLASHBACK_SIZE NUMBER

Which two statements regarding the V$FLASHBACK_DATABASE_STAT view are true? (Choose two.)

A.BEGIN_TIME is the time at which Flashback logging is enabled.

B.END_TIME is the time at which the query is executed on the view.

C.REDO_DATA is the number of bytes of redo data written during the interval.

D.This view contains information about flashback data pertaining to the last 24 hours.

E.FLASHBACK_DATA is the amount of flashback data generated since the database was opened.

答案:CD

解析:

V$FLASHBACK_DATABASE_STAT 记录的是过去24 小时的flashback 区读写统计

-- 每小时采样一次,并记录在该视图相应的数据字典中,BEGIN_TIME DATE,

END_TIME DATE 这两个参数是采样开始和结束时间。

V$flashback_database_stat 这个视图用来对Flashback log 空间情况进行更细粒度的记录和估计。 这个视图以小时为单位记录单位时间内数据库的活动量,Flashback_Data 代表Flashback log 产生数量,DB_Date 代表数据改变数量,Redo_Date 代表日志数量,通过这3 个数量可以反映出数据的活动特点,更准确的预计Flash Recovery Area 的空间需求



12. View the Exhibit.

You have more than one table in the recycle bin having the same original name, DEPT2. You do not have any table with the name DEPT2 in your schema. You executed the following command:

PURGE TABLE dept2;

Which statement is correct in this scenario?

A.All the tables having the same original name as DEPT2 will be purged from the recycle bin.

B.The table with dropscn = 1928151 (oldest dropscn) will be purged from the recycle bin.

C.The table with dropscn = 1937123 (most recent dropscn) will be purged from the recycle bin.

D.None of the tables will be purged because there are multiple entries with the same original name in the recycle bin

答案:B

解析:

purge 从recycle 里面删除drop 掉的表

还原表按后进先出 (LIFO) 算法.

清除时,先进先出 (FIFO) 算法自动将回收站对象从回收站中清除.

13. On Monday, you dropped the DEPT table from your schema and then you re-created the DEPT table in your schema. On Wednesday, you have a requirement to restore the DEPT table from the recycle bin.

Which statement is correct?

A.You can restore the DEPT table by using the Oracle Flashback Drop feature, provided you use the RENAME TO clause.

B.You can restore the DEPT table by using the Oracle Flashback Drop feature and a system-generated name will be assigned to the restored table.

C.You cannot restore the DEPT table by using the Oracle Flashback Drop feature because a table with the name DEPT already exists in your schema.

D.You cannot restore the DEPT table by using the Oracle Flashback Drop feature because the contents of the recycle bin are purged every 12 hours by default.

答案:A

解析:

Flashback table 语句同时提供了一个rename to 的子句,如果要恢复的表

在当前的schema 中已经,存在同名的表,建议你在恢复时通过rename to 子句为

待恢复的表指定一个新的表名,不然数据库会报ORA-38312

Flashback table DEPT2 to before drop rename to dept



14. Which two statements are correct regarding the Oracle Flashback Drop feature? (Choose two.)

A.Recycle bin exists for the tables only in non-SYSTEM, locally managed tablespaces.

B.You can flash back a dropped table provided row movement has been enabled on the table.

C.If you drop an index before dropping its associated table, then the recovery of the index is not supported when you flash back the dropped table.

D.When you execute the DROP TABLESPACE INCLUDING CONTENTS command, the objects in the tablespace are placed in the recycle bin.

E.When a dropped table is moved to the recycle bin, only the table is renamed to a system-generated name; its associated objects and constraints are not renamed.

F.If you drop a table that is protected by the recycle bin, then associated bitmap-joined indexes and materialized view logs are also stored in the recycle bin.

答案:AC

解析:

基于Recycle Bin 的表恢复

(1)Flashback Drop 不能恢复参照完整性,这很容易理解,毕竟在该表删除之

后,被参照表是否有修改,它已经无法控制了,因此如果该表有主外键约束的话,

恢复之后,该约束是DISABLE 状态,需要DBA 手工处理。

(2)所操作的表必须是存在于本地管理表空间中。Flashback Drop 不能恢复字典管理表空间中被删除的表。

(3)被恢复的表的关联对象,如其索引、约束的名称不会自动恢复成删除前的名称,而是系统自动生成的名称,如果你对表的索引、约束有相应命名规范,那在恢复表之后,需要DBA 手工将索引、约束等改名。另外位图索引不能被恢复,因为删除表时位图索引信息并不会被放入Recycle Bin 中。

(4)当删除表时,依赖于该表的物化视图也会同时删除,但是由于物化视图并不会被放入Recycle Bin,因此当你执行FLASHBACK TABLE TO BEFORE DROP时,也不能恢复依赖其的物化视图,需要DBA 手工介入重新创建。

(5)相对于被删除的表而言,当数据文件空间不足时,Oracle 会首先清理被删除表的索引,因此假如你执行FLASHBACK TABLE TO BEFORE DROP 后发现恢复出来的数据缺少索引可能是正常的,说明你显然错过了最佳的恢复时机。

(6)Flashback Drop 支持同时操作多个表,表名中间以逗号分隔,如果你执行一条Flashback Table 命令时同时指定了多个表,要记住单个Flashback Table是在同一个事务中,因此这些表的恢复操作要么都成功,要么都失败。

(7)Flashback Drop 只能恢复DROP 命令删除的表,如果你通过TRUNCATE 命令清空表中数据,然后又希望恢复,对于这种情况不管是Flashback Table 还是Flashback Query 都无能为力,唯一能恢复TRUNCATE 操作的Flashback 特性是Flashback Database,不过代价也比较大。

Flashback table table_name to scn(恢复被删除的记录)才需要启动row movement;故B 错



15. View the Exhibit and examine the Flashback SCNs.

A user has inserted wrong department data in the DEPT3 table in the USERS tablespace. You use the Flashback Table functionality to rectify the erroneous inserts. While performing the recovery, you chose

2004343 as the Flashback SCN.

Which two statements are correct in this scenario? (Choose two.)

A.Only the row with DEPARTMENT_ID 290 would be flashed back.

B.The rows with DEPARTMENT_ID 290 and 300 would be flashed back.

C.The rows with DEPARTMENT_ID 290 and 280 would be flashed back.

D.You would have taken the USERS tablespace offline before starting the Flashback Table operation.

E.You would have enabled row movement for the DEPT3 table before starting the Flashback Table operation.

答案:BE

解析:

The prerequisites for performing a FLASHBACK TABLE operation are as follows:

.You must have been granted the FLASHBACK ANY TABLE system privilege or you must have the FLASHBACK object privilege on the table.

.You must have SELECT, INSERT, DELETE, and ALTER privileges on the table.

.Undo information retained in the undo tablespace must go far enough back in time to satisfy the specified target point in time or SCN for the FLASHBACK TABLE operation.

.Row movement must be enabled on the table for which you are issuing the FLASHBACK TABLE statement. You can enable row movement with the following SQL statement:

ALTER TABLE table ENABLE ROW MOVEMENT;

SQL> flashback table test to timestamp('2010-09-09 14:26:49');

flashback table test to timestamp('2010-09-09 14:26:49')

第 1 行出现错误:

ORA-08189: 因为未启用行移动功能, 不能闪回表

SQL> alter table test enable row movement;

表已更改。

SQL> flashback table test to timestamp to_timestamp('2010-09-09 14:26:49','YYYY-MM-DD HH24:MI:SS');

闪回完成。


16. You are working in an online transaction processing (OLTP) environment. You used the FLASHBACK TABLE command to flash back the CUSTOMERS table. Before executing the FLASHBACK TABLE command, the System Change Number (SCN) was 663571. After flashing back the CUSTOMERS table,you realize that the table is not in the correct state and the resultant changes are not what you had

desired. So, you need to reverse the effects of the FLASHBACK TABLE command while ensuring that:

a) No other user data in the database is affected.

b) The operation takes the minimum possible time.

Which option would you choose?

A.use the ROLLBACK command with SCN 663571

B.perform. Flashback Transaction Query with SCN 663571

C.execute the FLASHBACK DATABASE statement to retrieve the CUSTOMERS table as it was at SCN 663571

D.execute another FLASHBACK TABLE statement to retrieve the CUSTOMERS table as it was at SCN 663571

答案:D

解析:Flashback table 后发现数据不对,提出要求一是不影响其它数据二是要快,那么再闪回一次就行了



17. You executed the following FLASHBACK TABLE command:

FLASHBACK TABLE emp TO TIMESTAMP ('11:45','hh12:mi');

Which two statements are correct? (Choose two.)

A.The FLASHBACK TABLE statement will not be written to the alert log file.

B.The changes made to the EMP table since the specified time will be undone.

C.The EMP table that was dropped by mistake from the database will be restored.

D.The FLASHBACK TABLE statement will be executed within a single transaction.

E.The FLASHBACK TABLE statement will not maintain the existing indexes on the EMP table.

F.The list of transactions that have modified the EMP table since the specified time will be displayed.

答案:BD

解析:

a、Flashback table 肯定会被写到alert 中

b、使用scn 闪回,肯定是使用的undo 里面的数据,

c、如果一个表被删除后是否还是可以使用闪回表呢(不能)

flashback table test5 to before drop;

d、在一个transaction 中,闪回将被执行

e、闪回表后,同时会恢复在其上的索引



18. Why would you use the following FLASHBACK TABLE command?

FLASHBACK TABLE emp TO TIMESTAMP ('11:45','hh12:mi');

A.to undo the changes made to the EMP table since the specified time

B.to restore the EMP table that was wrongly dropped from the database

C.to view the transactions that have modified the EMP table since the specified time

D.to view the changes made to the EMP table for one or more rows since the specified time

E.to recover the EMP table to a point in time in the past by restoring the most recent backup

答案:A

解析:

SQL> select sysdate from dual;

SYSDATE

-------------------

2010-09-09 14:26:49

SQL> select * from test;

未选定行

SQL> insert into test values(1);

已创建 1 行。

SQL> commit;

提交完成。

SQL> flashback table test to timestamp to_timestamp('2010-09-09 14:26:49','YYYY-MM-DD HH24:MI:SS');

闪回完成。

SQL> select * from test;

未选定行



19. For which two SQL statements can you use the Flashback Table feature to revert a table to its previous state? (Choose two.)

A.UPDATE TABLE

B.CREATE CLUSTER

C.TRUNCATE TABLE

D.ALTER TABLE MOVE

E.INSERT INTO...VALUES

F.ALTER TABLE...DROP COLUMN

G.ALTER TABLE...DROP PARTITION

答案:AE

解析:

哪两种sql 语句可以使用闪回表

a、update

b、insert

这应该证明drop 表或者truncate 表是无法使用闪回的,同时改变表的结构也是不行的



20. You are working in an online transaction processing (OLTP) environment. You realize that the salary for an employee, John, has been accidentally modified in the EMPLOYEES table. Two days ago, the data was in the correct state. Flashback logs generated during last two days are available in the flash recovery area.

Which option would you choose to bring the data to the correct state while ensuring that no other data in the same table is affected?

A.perform. point-in-time recovery

B.perform. a Flashback Table operation to restore the table to the state it was in two days ago

C.perform. a Flashback Database operation to restore the database to the state it was in two days ago

D.perform. Flashback Versions Query and Flashback Transaction Query to determine all the necessary undo SQL statements, and then use them for recovery

答案:D

解析:Flashback Query 只能看到某一点的对象状态,Flashback Version Query 可以看到过去某个时间段内,记录的演变历史。

(快速定位,因为是错误的修改表记录,只能闪回查询)



21. View the Exhibits.

You performed operations on the DEPT4 table as shown in the Exhibit. When you perform. the FlashbackVersions Query, you find that the first two updates are not listed.

What could be the reason?

A.The row movement is not enabled on the table.

B.The first two updates were not explicitly committed.

C.The Flashback Versions Query lists only the most recent update.

D.The Flashback Versions Query stops producing rows after it encounters a time in the past when the table structure was changed.

答案:D

解析:

在哪种情况下可以使用flashback versions query

a、只能是commited 以后的数据

b、只能是dml 语句,ddl 不行,ddl 以后,前面的dml 也查询不到

c、没必要非要启用row movement



22. Which two statements are correct regarding the Flashback Versions Query feature? (Choose two.)

A.You can use this feature to identify the versions of V$ views.

B.You can use this feature to identify the versions of external and fixed tables.

C.You can use this feature for a table only if row movement is enabled for the table.

D.You can use this feature to identify the committed versions of the rows, but not the uncommitted versions.

E.You can use this feature to identify the inserts, deletes, and updates performed on a particular row but not the data definition language (DDL) operations performed on the table.

答案:DE

解析:详见上题



23. By mistake, you ran the batch job (for updating the BILL_DETAILS table) twice. You are not sure which rows in the BILL_DETAILS table were affected. You need to identify:

a) a list of changes made along with the transaction identifier of each change

b) the necessary SQL statements to undo the erroneous changes

Which option would you choose?

A.RMAN only

B.Flashback Table only

C.Flashback Versions Query only

D.Flashback Database and Flashback Transaction Query

E.Flashback Versions Query and Flashback Transaction Query

答案:E

解析:

Flashback Query 只能看到某一点的对象状态,Flashback Version Query 可以看到过去某个时间段内,记录的演变历史。

(快速定位,因为是错误的修改表记录,只能闪回查询)



24. You executed the following query:

SELECT operation, undo_sql, table_name

FROM flashback_transaction_query;

Which statement is correct regarding the query output?

A.It would return information regarding only the last committed transaction.

B.It would return only the active transactions in all the undo segments in the database.

C.It would return only the committed transactions in all the undo segments in the database.

D.It would return both active and committed transactions in all the undo segments in the database.

E.It would return information regarding the transactions that began and were committed in the last 30 minutes.

答案:D

解析:

select sum(bytes / 1024 / 1024), status, tablespace_name

from dba_undo_extents group by status, tablespace_name;

该查询将返回以STATUS 分组的各状态回滚信息所使用的空间量,一般存在三种STATUS 状态:

EXPIRED,UNEXPIRED,ACTIVE。ACTIVE 表示目前仍活跃的事务相关回滚信息,UNEXPIRED

表示虽然事务已经结束但回滚信息保留的时间仍未超过实例参数UNDO_RETENTION 所设定的值,EXPIRED 表示回滚信息保留时间已超过UNDO_RETENTION 所设定的值。

在UNDO 表空间未启用guarantee 选项的情况下(当前使用情况),新事务的回滚空间分配

遵循以下依据:

a) 寻找不存在ACTIVE 区间的回滚段,若没有则创建一个新的回滚段,若空间不允许生成新段,则返回错误。

b) 如果有一个回滚段被选中,但是其中空闲的空间并不足以存储该事务的回滚信息,那么它将尝试创建区间,如果表空间上没有空间,那么将会进入下一步。

c) 如果创建新区间失败,它将会搜索其他回滚段中的EXPIRED 区间并重用。

d) 如果其他回滚段中没有EXPIRED 区间可使用,那么它会继续搜索其他回滚段中

UNEXPIRED 区间并重用,注意事务不会重用本回滚段中的UNEXPIRED 区间,故UNEXPIRED 的

回滚空间仅部分可以为Oracle 重用;若仍得不到所需则返回错误。

结论(warehouse):flashback_transaction_query 中的数据来自undo datafile,只要事务

对应的before image 在undo datafile 中存在,flashback_transaction_query 里面就可

以查询到数据...目前没发现受那个参数的制约



25. By using the transaction identifier provided by _____ for a particular row change, you can use theFlashback Transaction Query to see the operation performed by the transaction.

A.Flashback Table

B.Flashback Database

C.Flashback Versions Query

D.the RMAN REPORT command

E.the DBA_PENDING_TRANSACTIONS view

答案:C

解析:

a.flashback versions query

flashback versions query 能够得到某个时间段内,某些数据行的所有不同版本。这里的版本以事务为单位,事务中的每次数据变化就是一个版本

b.flashback transaction query

flashback transaction query 其实就是查询历史的事务信息,通过查询,我们可以得到过去某个事务操作信息,包括改变的数据行rowid,事务开始和结束时间,事务对应的loggon user,以及用来撤销某个数据行改变的undo sql等。



26. There was media failure and you need to check the data files for any block corruption. Which option would you use to create a report on any corruptions found within the database?

A.the DBNEWID utility

B.the DBVERIFY utility

C.the ANALYZE command

D.the RMAN REPORT command

E.the RMAN CROSSCHECK command

F.the CHECK_OBJECT procedure of the DBMS_REPAIR package

答案:B

解析:

DBVERIFY:是一种外部命令行实用程序,可以对脱机或联机的数据库执行物理数据结构完整性检查。可以对备份文件与联机文件(或文件片段)运行此实用程序。只能检查数据文件;不能检查重做日志文件

ANALYZE:使用 ANALYZE 命令可以验证表或表分区的结构,以及索引或索引分区的结构。

要分析的对象必须位于本地计算机,并且必须是在您自己的方案中,或者必须拥有ANALYZEANY 系统权限。CASCADE 选项可以验证对象,包括该对象的所有相关对象。不将块标记为软损坏;只报告软损坏情况

RMAN CROSSCHECK:当手工删除了归档日志以后,Rman 备份会检测到日志缺失,从而无法进一步继续执行。所以此时需要手工执行crosscheck 过程,之后Rman 备份可以恢复正常。



27. The EMPLOYEES table is stored in the USERS tablespace. You need to check if the EMPLOYEES table is affected by the block corruption found in the USERS tablespace. Which option would you use?

A.the DBNEWID utility

B.the ANALYZE command

C.the RMAN LIST command

D.the RMAN REPORT command

E.the RMAN CROSSCHECK command

F.the RMAN BLOCKRECOVER command

答案:B

解析:见上题



28. The DB_BLOCK_CHECKING initialization parameter is set to FALSE. What level of block checking would be performed?

A.The Oracle database will not perform. block checking for any of the data blocks.

B.The Oracle database will perform. block checking for the default permanent tablespace only.

C.The Oracle database will perform. block checking for the data blocks in all user tablespaces.

D.The Oracle database will perform. block checking for the data blocks in the SYSTEM tablespace only.

E.The Oracle database will perform. block checking for the data blocks in the SYSTEM and SYSAUX tablespaces.

答案:D

解析:

OFF - no block checking is performed for blocks in the user tablespaces. However, semantic block checking for SYSTEM tablespace blocks is always turned on.

LOW - basic block header checks are performed after block contents change in memory (for example, after UPDATE or INSERT statements, on-disk reads, or inter-instance block transfers in RAC)

MEDIUM - all LOW checks are performed, as well as semantic block checking for all non-index-organized table blocks

FULL - all LOW and MEDIUM checks are performed, as well as semantic checks for index blocks (that is, blocks of subordinate objects that can actually be dropped and reconstructed when faced with corruption)



29. The DB_BLOCK_CHECKING initialization parameter is set to TRUE. What would be the result of this setting on the data blocks being written to the datafiles, every time the DBWn writes?

A.The Oracle database will check all data blocks by going through the data on each block, making sure the data is self-consistent.

B.DBWn and the direct loader will calculate a checksum and store it in the cache header of every data block when writing it to disk.

C.The Oracle database will check data blocks belonging to the SYSTEM tablespace only, by going through the data on each block, making sure the data is self-consistent.

D.The Oracle database will check data blocks belonging to the SYSAUX tablespace only, by going through the data on each block, making sure the data is self-consistent.

E.The Oracle database will check data blocks in the SYSTEM and SYSAUX tablespaces only, by going through the data on each block, making sure the data is self-consistent

答案:A

解析:Oracle checks a block by going through the data in the block, making sure it is logically self-consistent.



30. Your database is open and running in ARCHIVELOG mode. You take RMAN full backups every Sunday night. On Monday morning, while querying the user1.employees table, you receive the following error message:

01578: ORACLE data block corrupted (file # 5, block # 51) ORA-01110: data file 5:

'/u01/app/oracle/oradata/orcl/example01.dbf'

You need to rectify the corruption while ensuring the following:

The data file should remain online.

The mean time to recover (MTTR) should be minimal.

You are not using a backup control file, and all the archived logs are accessible.

Which option would you choose?

A.flash back the corrupted blocks

B.use the DBMS_REPAIR package

C.use the RMAN TSPITR command

D.use the RMAN BLOCKRECOVER command

E.use the RESTORE DATABASE and RECOVER DATABASE commands

F.investigate the time at which the corruption occurred and perform. a point-in-time recovery

答案:D

解析:

数据库在归档模式下,每个星期天进行一次全备份,星期一早晨发现数据块损坏,要求MTTR 时间最少,要求data file 在线,所以最好的方法就是RMAN BLOCKRECOVER



31. You are performing a block media recovery on the tools01.dbf data file in the SALES database by using RMAN.

Which two statements are correct in this scenario? (Choose two.)

A.You must ensure that the SALES database is mounted or open.

B.You must restore a backup control file to perform. a block media recovery.

C.You must take the tools01.dbf data file offline before you start a block media recovery.

D.You must put the database in NOARCHIVELOG mode to perform. a block media recovery.

E.You can perform. only a complete media recovery of individual blocks; point-in-time recovery of individual data blocks is not supported.

答案:AE

解析:

数据库必须在mounted or open 状态下才可以使用RMAN BLOCKRECOVER

RMAN BLOCKRECOVER 始终执行完全恢复。使用BLOCKRECOVER 命令时,不能执行时间点恢复



32. You execute the following RMAN commands in the order shown below:

BACKUP VALIDATE DATABASE;

BLOCKRECOVER CORRUPTION LIST;

What will these commands do?

A.create a backup of the database and recover all corrupted blocks found in the backup

B.run a backup validation and list all the logically corrupt blocks as well as physically corrupt blocks in the database

C.run a backup validation to populate V$COPY_CORRUPTION view, and then list any corrupt blocks recorded in the view

D.run a backup validation to populate V$DATABASE_BLOCK_CORRUPTION view, and then repair any

corrupt blocks recorded in the view

E.run a backup validation, repair any corrupt blocks found during the validation process, and then update

V$DATABASE_BLOCK_CORRUPTION view to indicate which corrupt blocks have been repaired

答案:D

解析:

backup validate database;

--检查所有数据文件是否存在坏块,并不执行实际备份, 这个时候,访问

v$database_block_corruption 可以看到详细的坏块的信息.

执行BLOCKRECOVER CORRUPTION LIST,会自动按V$DATABASE_BLOCK_CORRUPTION 进行修复。V$DATABASE_BLOCK_CORRUPTION 视图显示当前损坏的数据库块的列表。



33. What are the two advantages of RMAN Block Media Recovery (BMR) over file-level recovery?(Choose two.)

A.BMR lowers the mean time to recover (MTTR).

B.BMR supports point-in-time recovery of individual data blocks.

C.BMR enables you to use incremental backups for block recovery.

D.BMR enables recovery even when the database is not mounted or open.

E.BMR enables you to use proxy backups to perform. block media recovery.

F.BMR enables increased availability of data during recovery because the data file that requires a recovery can remain online.

答案:AF

解析:

使用RMAN Block Media Recovery (BMR)的好处

a、减少MTTR 的时间

b、由于正在恢复的数据文件继续保持联机状态,所以可以提高数据在介质恢复期间的可用性。

对于选项c 的结论:

You must have a full backup of the file containing the corrupt blocks:block media recovery cannot use incremental backups.

Level 0,或者在无Level 0 可用的备份下做的Level 1 的增量备份都是一个完整的包含了损坏的块的备份,所以应该也是可以用来执行Block Media Recovery 的.只是说当使用过Level 0,或者在无Level 0 可用的备份下做的Level 1 的增量备份后不会使用更高Level

的增量备份进行恢复,而只会采用应用Archived log files 的方式进行恢复



34. You observe that database performance has degraded over a period of time. While investigating the reason, you find that the size of the database buffer cache is not large enough to cache all the needed

data blocks.

Which advisory component would you refer to, in order to determine the required size of the database buffer cache?

A.Memory Advisor

B.Segment Advisor

C.SQL Tuning Advisor

D.SQL Access Advisor

E.Automatic Database Diagnostic Monitor (ADDM)

答案:A

解析:

你发现你的数据高速缓存区(Database Buffer Cache)不够用了,可以使用Memory Advisor 来确定其大小,自动数据库诊断监视器(ADDM):执行自上而下的实例分析,确定问题和潜在的原因,并提供修复问题的建议案。ADDM 可潜在地调用其他指导。SGA 指导(Memory

Advisor):根据系统全局区(SGA) 中各个组件的访问模式,负责优化和建议SGA 的大小。



35. View the Exhibit and examine the characteristics of the USERS tablespace.

You observe that a large volume of inserts and deletes are happening on the TRANS table in the USERS tablespace and you suspect that the TRANS table is fragmented.

Which advisory component would you refer to, in order to find information about table fragmentation?

A.Memory Advisor

B.Segment Advisor

C.SQL Tuning Advisor

D.SQL Access Advisor

E.Automatic Database Diagnostic Monitor (ADDM)

答案:B

解析:

SQL Tuning Advisor: Provides tuning advice for SQL statements

SQL Access Advisor: Deals with schema issues and determines optimal data access paths,such as indexes and materialized views

Segment Advisor: Monitors object space issues and analyzes growth trends



36. You find that the execution time of reports in your datawarehouse application is significantly high. You suspect the lack of indexes to be the reason for the degradation in performance.

Which advisory component would you refer to, in order to determine the appropriate indexes?

A.Memory Advisor

B.Segment Advisor

C.SQL Access Advisor

D.Automatic Workload Repository (AWR)

E.Automatic Database Diagnostic Monitor (ADDM)

答案:C

解析:

你发现你的数据仓库中的执行报告时间非常慢,你怀疑是缺少相应的索引,可以使用SQL Access Advisor(SQL 访问指导)

SQL 访问指导:处理方案问题并确定最佳数据访问路径(如索引和实体化视图) 。实体化视图=物化试图

物化视图是包括一个查询结果的数据库对像,它是远程数据的的本地副本,或者用来生成基于数据表求和的汇总表。物化视图存储基于远程表的数据,也可以称为快照。



37. You want to use the SQL Tuning Advisor to generate recommendations for badly written SQL statements in your development environment.

Which three sources can you select for the advisor to analyze? (Choose three.)

A.Top SQL

B.snapshots

C.SQL Tuning sets

D.index access path

E.optimizer statistics

F.materialized view logs

答案:ABC

解析:

Using the SQL Tuning Advisor

• Use the SQL Tuning Advisor to analyze SQL statements and obtain

performance recommendations.

• Sources for SQL Tuning Advisor to analyze:

– Top SQL: Analyzes the top SQL statements currently active

– SQL Tuning Sets: Analyzes a set of SQL statements you provide

– Snapshots: Analyzes a snapshot

– Baselines: Analyzes a baseline



38. View the Exhibit.

In your production database, the total waits and the time waited for log file parallel write are significantly high. While investigating the reason, you find that there are three redo log groups with two members in

each group, and all redo log members are placed on a single physical disk.

What action would you take to minimize the waits?

A.start the log writer slave processes

B.increase the number of redo log files

C.increase the size of the redo log buffer

D.place the redo log files on different disks

E.increase the number of log writer processes

答案:D

解析:把日志建在不同的磁盘上来分散i/o 压力,提高写入速度



39. In your production database, you have observed that the database server performance degrades whenever there is a switch between the log groups. On further investigation, you find that the database is running in ARCHIVELOG mode and the archived log files are being written to the same disk that is used to store the redo log members.

Which two actions would you take to improve the performance of the database server? (Choose two.)

A.increase the size of the redo log buffer

B.increase the number of redo log groups

C.increase the number of log writer processes

D.increase the number of ARCn processes

E.change the appropriate LOG_ARCHIVE_DEST_n parameter to place the archived log files in a separate location

答案:BE

解析:

增加 redo log groups 可以留更多的时间给ARCn进行归档

比如现在有2个redo log group,1组和2组,1组为当前组

当1组的日志写满后切换到2组,ARCn开始对1组进行归档,归档未完成前,2组又写满了,此时要等到1组的归档完成后才能切换回1组,所以此时出现了等待时间影响了性能。

如果有足够多的组,在切换前归档已经完成,就不存在题中的问题了

把日志建在不同的磁盘上来分散i/o 压力,提高写入速度



40. Your production database is running in the ARCHIVELOG mode and the ARCn process is functional.

You have two online redo log groups. Which three background processes would be involved when a log switch happens? (Choose three.)

A.archival

B.log writer

C.database writer

D.system monitor

E.process monitor

F.change tracking writer

答案:ABC

解析:

Block change tracking 进程记录自从上一次备份以来数据块的变化,并把这些信息记录在跟踪文件中。RMAN 使用这个文件判断增量备份中需要备份的变更数据。这极大的促进了备份性能,RMAN 可以不再扫描整个文件以查找变更数据。为此Oracle 引入了一个新的后台进程,CTWR,其全称为Change Tracking Writer,用于记录变化的块并将变化写入相应的日志文件中。



41. In the parameter file of your production database, the FAST_START_MTTR_TARGET parameter is

set to 300 to optimize instance recovery. While observing the performance of the database during instance recovery, you find that the redo log files are not sized properly to support this activity.

Which two sources could you use to determine the optimal size of the redo log files? (Choose two.)

A.the V$LOG view

B.the V$DBFILE view

C.the V$LOGFILE view

D.the V$INSTANCE_RECOVERY view

E.Oracle Enterprise Manager Database Control

答案:DE

解析:

FAST_START_MTTR_TARGET:实例恢复的时间限制,oracle将这个时间换算成redo blocks数量,当log buffer中未写入log file的redo block数量超过这个值,就会触发增量检查点。

v$instance_recovery 视图的optimal_logfile_size 列通过显示MTTR 尺寸的最佳重做日志尺寸,帮助你确定恰当的重做日志尺寸。Oracle 建议所有联机重做日志至少与optimal_logfile_size 列值所指定的相同。



42. In which two conditions are resumable statements suspended? (Choose two.)

A.when a user session is terminated

B.when a user exceeds the space quota

C.when a user manually suspends the statement

D.when the maximum extents of a segment is reached

E.when a table that is being accessed by the current transaction is not found

答案:BD

解析:

当出现空间不足等相关的错误时,Oracle 可以不是马上返回错误信息,并回滚当前的操作,而是将操作挂起直到挂起时间超过RESUMABLE TIMEOUT,或者空间不足的错误被解决



43. Which type of PL/SQL construct would you use to automatically correct the error resulting from a statement that was suspended due to a space-related problem?

A.function

B.package

C.procedure

D.database trigger

E.anonymous PL/SQL block

答案:D

解析:

触发器是存储在数据库中的 PL/SQL 代码对象,它们会在某些事件发生时自动运行或“触发”。Oracle 数据库允许许多操作充当触发事件,包括插入到表中、用户登录数据库以及尝试删除表或更改审计设置等操作。



44. The warning and critical threshold values have been set to 85% and 97%, respectively, for one of the tablespaces. The current tablespace space usage is 54%. You modify the warning threshold to be 50% and critical threshold to be 53% in Database Control.

Which statement is true?

A.The new setting would be applied but no alerts would be raised immediately.

B.The new setting would be applied and an alert would be raised immediately.

C.The new setting would be ignored because the tablespace space usage is more than the specified threshold value.

D.The new setting would cause an error because the tablespace space usage is more than the specified threshold value.

答案:A

解析:

当你更改了警告和严重的门限后(往小改,已经达到了门限),该更改会立即生效,但是数据库不会立即产生告警。



45. In an Oracle 10g database, the in-memory statistics are gathered at regular intervals and used to perform. growth-trend analysis and capacity planning of the database. Which component stores these statistics?

A.recovery catalog

B.Oracle Enterprise Manager Repository

C.Automatic Workload Repository (AWR)

D.Oracle 10g Enterprise Manager Grid Control

E.Automatic Database Diagnostic Monitor (ADDM)

答案:C

解析:

自动工作量资料档案库 (AWR)

a、AWR 是为 Oracle Database 10g 组件提供服务的基础结构,通过这个基础结构可收集、维护和利用统计信息,以便检测问题和进行自优化。可将这个基础结构视为包含数据库统计信息、度量等内容的数据仓库。

b、默认情况下,数据库每隔 60 分钟从SGA 中自动捕获一次统计信息,然后将

其以快照形式存储在 AWR 中

c.awr:auto workload repository 体系的核心

statspack 的进一步改进(不收集操作系统信息,没有db time 等)

awr 属于sys 用户,存在sysaux 表空间上

wri(internal 内部) wrm(metadata) wrh(history)

对这些表重新创建了视图 dba_hist_

select * from dba_hist_wr_control

每1 小时收集一次,在磁盘上保留7 天

可以用包修改exec

dbms_worload_repository.modify_snapshot_settings(retention=>1440,inte

rval=>30);

查看数据库性能报告,可以定位到时间段,10g 前不可能办到

oracle 每1 小时创建了一个快照(跟照片样,定格背景)

exec dbms_worload_repository.create_snapshot;

select * from dba_hist_snapshot order by snap_id desc

select * from dba_hist_undostat

查看awr 报告 选择开始快照 和结束快照 之间数据库不要重启

@e:...\rdbms\admin\awrrpt.sql

db time:所有活动session 的总时间

正常是两个值大致差不多,系统出问题的的时候 db time 比cpu 时间大很多,绝

大多数都在等待(算在db time 里)



46. You have specified the warning and critical threshold values of an application tablespace to be 60% and 70%, respectively. From the tablespace space usage metrics, you find that the actual space usage

has reached the specified warning threshold value, but no alerts have been generated.

What could be the reason for this?

A.The EVENT parameter was not set.

B.The SQL_TRACE parameter is set to FALSE.

C.The Enterprise Manager Grid Control is not used.

D.The STATISTICS_LEVEL parameter is set to BASIC.

E.The TIMED_STATISTICS parameter is set to FALSE.

答案:D

解析:

statistics_level 默认是typical,在10g 中表监控是激活的,强烈建议在10g 中此参数的值是typical.如果STATISTICS_LEVEL 设置为basic,不仅不能监控表,而且将禁掉如下一些10g 的新功能:

ASH(Active Session History)

ASSM(Automatic Shared Memory Management)

AWR(Automatic Workload Repository)

ADDM(Automatic Database Diagnostic Monitor)



47. View the Exhibit and examine the properties of the TT tablespace.

Using Database Control, you have scheduled a job to shrink the TRANS table residing on the TT tablespace. The job would run at 5:00 p.m. every Friday.When you examine the space usage of the table after the completion of the job, you find that the table has not been shrunk.

What could have been the reason for this?

A.The tablespace that contains the TRANS table is online.

B.The tablespace that contains the TRANS table is permanent.

C.The tablespace that contains the TRANS table is locally managed.

D.The segment space management of the tablespace that contains the TRANS table is manual in nature.

答案:D

解析:

Shrink 优点:

1: shrink 命令让表缩小,cascade 命令会让相关的索引也同时缩小。

2: 执行shrink 命令的时候就不需要rebuild index。而执行move 命令之后无法使用index,所以无法利用index 查找。要解决这个问题让index 恢复可以使用的状态,必须对index 进行rebuild。

3:即使对象所在表空间几乎没有空闲空间,shrink 命令也能执行。

SQL> alter table emp shrink space;

Table altered.

SQL> alter table emp move;

AUTOSEG_TST 表空间没有足够的空闲空间。

Shrink 缺点:

1.无法解除行迁移

2.必须是local 管理的自动段管理

3.不可以是下面的段:

-集群(cluster)、集群化表

-包含long 列的物件

-LOB 段

-包含函数索引(function index)的表

另外move 命令的执行时间很短,根据情况选择



48. View the Exhibit and examine the properties of the USERS tablespace.

You execute the following statement to shrink the TRANS table existing on the USERS tablespace:

SQL> ALTER TABLE trans SHRINK SPACE CASCADE;

Which objects would be affected by this command? (Choose all that apply.)

A.the TRANS table

B.the B*Tree indexes on the TRANS table

C.the materialized views log of the TRANS table

D.the materialized views based on the TRANS table

E.the large object (LOB) segments of the TRANS table

答案:AB

解析:

使用shrink space 时,索引会自动维护。如果在业务繁忙时做压缩,可以先shrink space compact,来压缩数据而不移动HWM,等到不繁忙的时候再shrink space 来移动HWM。

Move 会移动高水位,但不会释放申请的空间,是在高水位以下(below HWM)的操作。而shrink space 同样会移动高水位,但也会释放申请的空间,是在高水位上下(below and above HWM)都有的操作。

shrink 有两个前提条件:

1、表必须启用row movement(rowid 要发生变化)

2、表段所在表空间的段空间管理(segment space management)必须为auto



49. In one of your online transaction processing (OLTP) applications, users are manipulating and querying a database table simultaneously. From the Segment Advisor, you find that one of the tables is highly fragmented and you want to shrink the table immediately without affecting the currently active queries.

Which option would you use with the ALTER TABLE command to achieve this objective?

A.REBUILD

B.CASCADE

C.TRUNCATE

D.ROW MOVEMENT

E.SHRINK SPACE COMPACT

F.SHRINK SPACE CASCADE

答案:E

解析:

alter table table_name shrink space;

後面两个参数:cascade,compact;

compact(紧凑的,简洁的):加此参数为了当系统负载比较大时,做此作可以减小性能影响。在负载比较轻时,在作一次alter table table_name shrink

space;就可以了。

cascade:加上此参数会shrink table 上的索引,也相当如rebuild index;



50. While designing the database for one of your online transaction processing (OLTP) applications, you want to achieve the following:

a) high availability of data

b) faster primary key access to the table data

c) compact storage for the table

Which type of tables would you use to achieve these objectives?

A.heap tables

B.object tables

C.partitioned tables

D.index-organized tables (IOTs)

答案:D

解析:

Index-organized tables provide faster access to table rows by the primary key or any key that is a valid prefix of the primary key.Because rows are stored in primary key order, a significant amount of additional storage space savings can be obtained through the use of key compression.Use of primary-key based logical rowids, as opposed to physical rowids,

in secondary indexes on index-organized tables allows high availability.

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