OCP 1Z0-023 学习讨论区

Hollie

我几个问题想请教一下各位：
1. When you create a database what is the minimum number of redo log group and members required?
a. 1 Group, 1 member
b. 2 Groups, 1 member each
c. 2 Groups, 2 members each *
d. 4 Groups, 1 member each

2. Which data dictionary views contain all of the object privileges for  all users?
a. DBA_TAB_PRIVS and DBA_COL_PRIVS  *
b. DBA_SYS_PRIVS
c. DBA_TAB_PRIVS
d. DICTIONARY

3. Which database parameter can be changed for a existing database and take affect after re-start the instance?   (Choose three)
a. background_dump_dest
b. db_block_size     *
c. db_block_buffer   *
d. log_buffer        *

我的选择是对的吗？

33281

关于create read-only tablespaceon on a write-once device
书上说：

1ALTER TABLESPACE....READ ONLY
2use OS command to move the data files of the TS to the
  read-only device
3ALTER TABLESPACE....RENAME DATAFILE

用以上三步实现把TS改建在光盘上使用，
其实以上三步所做的操作就相当于moving data file of TS，
但是为什么moving data file of TS需要offline TS,而它却不必offline呢？于是做以下测试：

实验环境：
OS：WIN98II
DB：ORACLE PERSON EDITION 8
CONNECT SYS/CHANGE_ON_INSTALL

SQL> ALTER TABLESPACE TS_TEST1 READ ONLY;
表空间已修改.

c:\>copy 'G:\TEMP\DATA01.DBF' TO 'G:\DATA01.DBF';
     （此处用硬盘模拟刻录光盘）

SQL> ALTER TABLESPACE TS_TEST1
     RENAME DATAFILE 'G:\TEMP\DATA01.DBF'
  2  TO 'G:\DATA01.DBF';
ERROR 发生在第 1 行:
ORA-01525: 更改数据文件名时出错
ORA-01121: 不能将数据库文件 10 改名 -
                  文件在使用中或在恢复中
ORA-01110: 数据文件 10: 'G:\TEMP\DATA01.DBF

果然报错！
看来要把TS改建为放于CDROM中的只读TS需要：

1OFFLINE TS
2DATAFILE COPY TO CDROM
3ALTER TABLESPACE 。。RENAME DATAFILE
4ALTER TABLESPACE ONLINE
5ALTER TABLESPACE 。。READ ONLY

但是STS中的考题答案是：
1ALTER TABLESPACE 。。READ ONLY
2DATAFILE COPY TO CDROM
3ALTER TABLESPACE 。。RENAME DATAFILE

Hollie

Hi,all
   我已知道the minimum number of redo log group and members required应是2 Groups, 1 member each
   又一问题请教
   If the group is active,why you must wait a log switch or force a log switch before dropping one of ites members?
   谢谢！

feng_xin

最初由 Hollie 发布
[B]我几个问题想请教一下各位：
1. When you create a database what is the minimum number of redo log group and members required?
a. 1 Group, 1 member
b. 2 Groups, 1 member each
c. 2 Groups, 2 members each *
d. 4 Groups, 1 member each

2. Which data dictionary views contain all of the object privileges for  all users?
a. DBA_TAB_PRIVS and DBA_COL_PRIVS  *
b. DBA_SYS_PRIVS
c. DBA_TAB_PRIVS
d. DICTIONARY

3. Which database parameter can be changed for a existing database and take affect after re-start the instance?   (Choose three)
a. background_dump_dest
b. db_block_size     *
c. db_block_buffer   *
d. log_buffer        *

我的选择是对的吗？ [/B]

我认为应该是
1. b     2. a   3. acd

feng_xin

最初由 33281 发布
[B]关于create read-only tablespaceon on a write-once device
书上说：

1ALTER TABLESPACE....READ ONLY
2use OS command to move the data files of the TS to the
  read-only device
3ALTER TABLESPACE....RENAME DATAFILE

用以上三步实现把TS改建在光盘上使用，
.....
[/B]

书上是这么写的
The ALTER TABLESPACE...READ ONLY Command
Making tablespaces read-only prevents further write operations on the data files in the
tablespace. Therefore, the data files can reside on read-only media, such as CD-ROMs
or write-once (WORM) drives. Read-only tablespaces eliminate the need to perform
backups of large, static portions of a database. Use the ALTER TABLESPACE SQL
command to change a tablespace to read-only or read-write.
ALTER TABLESPACE tablespace READ [ONLY | WRITE]
To create a read-only tablespace on a write-once device:
1 Issue the command ALTER TABLESPACE...READ ONLY.
2 Use an operating system command to move the data files of the tablespace to the
read-only device.
3 Issue the command ALTER TABLESPACE...RENAME DATAFILE.


Taking a Tablespace Offline
A tablespace is typically online so that the data contained within it is available to
database users. However, the database administrator might take a tablespace offline to:
• Make a portion of the database unavailable, while allowing normal access to the
remainder of the database
• Perform an offline tablespace backup (although a tablespace can be backed up
while online and in use)
• Recover a tablespace or data file while the database is open
[B]• Move a data file while the database is open[/B]


答案是不是省略了tablespace offline的步骤

dolphinli

我的答案和楼上的兄弟相同。

试试下面的代码：
1、ALTER TABLESPACE TS_TEST1 READ ONLY;
2、ALTER TABLESPACE TS_TEST1 OFFLINE;
3、copy 'G:\TEMP\DATA01.DBF' TO 'G:\DATA01.DBF';
4、ALTER TABLESPACE TS_TEST1
RENAME DATAFILE 'G:\TEMP\DATA01.DBF'
2 TO 'G:\DATA01.DBF';

dolphinli

我的答案和楼上的兄弟相同。

试试下面的代码：
1、ALTER TABLESPACE TS_TEST1 READ ONLY;
2、ALTER TABLESPACE TS_TEST1 OFFLINE;
3、copy 'G:\TEMP\DATA01.DBF' TO 'G:\DATA01.DBF';
4、ALTER TABLESPACE TS_TEST1
RENAME DATAFILE 'G:\TEMP\DATA01.DBF'
2 TO 'G:\DATA01.DBF';
5、ALTER TABLESPACE TS_TEST1 ONLINE;

Hollie

第三题为什么选择acd

33281

实验环境：
OS：WIN98II
DB：ORACLE PERSON EDITION 8
CONNECT SYS/CHANGE_ON_INSTALL
-----------------------------------------------------------------
SQL> alter database add logfile
2 ('g:\temp\redo1.log',
3 'g:\temp\redo2.log') size 1m;

数据库已删除.

SQL> select * from v$log;

GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS
--------- --------- --------- --------- --------- --- ---------
1 1 24 204800 1 NO INACTIVE
2 1 26 204800 1 NO CURRENT
3 1 0 1048576 2 YES UNUSED

SQL> alter database drop logfile group 3;

数据库已删除.

SQL> alter database add logfile
2 ('g:\temp\redo1.log',
3 'g:\temp\redo2.log');

数据库已删除.

SQL> alter database drop logfile group 3;

数据库已删除.

SQL> alter database add logfile
2 ('g:\temp\redo1.log',
3 'g:\temp\redo2.log') reuse;

数据库已删除.

===========================
以上使用已经存在的两个redo log file
建立一个新redo log group,
以上使用的两种方法均可建立新group
而这两种方法恰恰是错的，不可思议的是使用
STS上说的方法（后附）竟然报错：

SQL> 1 alter database add logfile
2 ('g:\temp\redo1.log' reuse,
3* 'g:\temp\redo2.log'reuse)

('g:\temp\redo1.log' reuse,
*
ERROR 发生在第 2 行:
ORA-00907: 缺少右括号
=========================

STS题：
Which statement will create a new redo log group
in the PROD database with three members
if the redo log files are 1M and already exist?
正确答案是：
ALTER DATABASE prod ADD LOGFILE GROUP 4
('/u01/oracle/prod/log4a.rdo' REUSE,
'/u01/oracle/prod/log4b.rdo' REUSE,
'/u01/oracle/prod/log4c.rdo REUSE');

feng_xin

最初由 Hollie 发布
[B]第三题为什么选择acd [/B]

3. Which database parameter can be changed for a existing database and take affect after re-start the instance? (Choose three)
a. background_dump_dest
b. db_block_size *
c. db_block_buffer *
d. log_buffer *


因为db_block_size一但建库后就不能修改。