[每日一题] 11gOCP 1z0-053 :2013-10-11 Flashback Data Archive属性.........................43
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正确答案：BD
闪回数据归档请参考：http://blog.csdn.net/guoyjoe/article/details/9199963
直接用实验解析答案
答案A，不开归档才也可以用Flashbackup Data Archive闪回数据归档，闪回数据归档与UNDO有关，与ARCHIVE LOG无关。
在没有归档下也可以创建闪回数据归档，操作如下：
（1）关闭归档
gyj@OCM> conn / as sysdba Connected. sys@OCM> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. sys@OCM> startup mount; ORACLE instance started. Total System Global Area 839282688 bytes Fixed Size 2233000 bytes Variable Size 436211032 bytes Database Buffers 394264576 bytes Redo Buffers 6574080 bytes Database mounted. sys@OCM> alter database noarchivelog; Database altered. sys@OCM> alter database open; Database altered. sys@OCM> archive log list; Database log mode No Archive Mode Automatic archival Disabled Archive destination /arch Oldest online log sequence 97 Current log sequence 99
sys@OCM> conn gyj/gyj Connected. gyj@OCM> create flashback archive flash1 tablespace gyj quota 10M retention 1 year; Flashback archive created.
说明没开归档下也可以创建闪回数据归档，所以A答案错。
答案B正确，只有在自动管理undo表空间才能创建闪回数据归档。
（1） UNDO自动管理
sys@OCM> conn gyj/gyj Connected. gyj@OCM> drop flashback archive flash1; Flashback archive dropped. gyj@OCM> show parameter undo NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_management string AUTO undo_retention integer 900 undo_tablespace string UNDOTBS1
（2） 创建闪回数据归档，成功
gyj@OCM> create flashback archive flash1 tablespace gyj quota 10M retention 1 year; Flashback archive created.
（3） UNDO手动管理
gyj@OCM> alter system set undo_management=manual scope=spfile; System altered. gyj@OCM> shutdown immediate; ORA-01031: insufficient privileges gyj@OCM> conn / as sysdba Connected. sys@OCM> startup force; ORACLE instance started. Total System Global Area 839282688 bytes Fixed Size 2233000 bytes Variable Size 436211032 bytes Database Buffers 394264576 bytes Redo Buffers 6574080 bytes Database mounted. Database opened. sys@OCM> show parameter undo NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_management string MANUAL undo_retention integer 900 undo_tablespace string UNDOTBS1
sys@OCM> createflashback archive flash2 tablespace tp1 quota 10M retention 1 year;
create flashbackarchive flash2 tablespace tp1 quota 10Mretention 1 year
*
ERROR at line 1:
ORA-55628: Flashback Archive supports Oracle 11g orhigher
所以答案B正确只有在自动管理的UNDO表空间下才能创建闪回数据归档
答案C，不正确，不需要设Undo retention为guarantee，默认Undo retention为 no guarantee就可以创建闪回数据归档，答AB都在no guarante下创建的闪回数据归档，能过如下视图查是不是NO GUARANTEE,看UNDOTBS1表空间是NOGUARANTEE
sys@OCM> SELECT TABLESPACE_NAME,RETENTION FROM DBA_TABLESPACES; TABLESPACE_NAME RETENTION ------------------------------ ----------- SYSTEM NOT APPLY SYSAUX NOT APPLY UNDOTBS1 NOGUARANTEE TEMP NOT APPLY USERS NOT APPLY EXAMPLE NOT APPLY GYJ NOT APPLY TP1 NOT APPLY MRKT NOT APPLY TEMP1 NOT APPLY TEMP4 NOT APPLY
答案D正确，表空间必须是ASSM才能创建闪回数据归档。上例是建在表空间TP1上是AUTO管理段的。
sys@OCM> SELECT TABLESPACE_NAME,SEGMENT_SPACE_MANAGEMENT FROM DBA_TABLESPACES; TABLESPACE_NAME SEGMEN ------------------------------ ------ SYSTEM MANUAL SYSAUX AUTO UNDOTBS1 MANUAL TEMP MANUAL USERS AUTO EXAMPLE AUTO GYJ AUTO TP1 AUTO MRKT AUTO TEMP1 MANUAL TEMP4 MANUAL
举个反例，我建个MSSM的表空间，看能不能创闪回数据归档：
sys@OCM> create tablespace tp2 datafile '/u01/app/oracle/oradata/ocm/tp2.dbf' size 100M Segment Space Management MANUAL;
Tablespace created.
sys@OCM> create flashback archive flash3 tablespace tp2 quota 10M retention 1 year;
create flashback archive flash3 tablespace tp2 quota 10M retention 1 year
*
ERROR at line 1:
ORA-55627: Flashback Archive tablespace must be ASSM tablespace
看到提示了吧，必须要用ASSM表空间。
所以说啊,学习OCP一定要一道道题认认真真做实验，操作->查资料->思考->总结（反复折腾才能真正才为大师啊，这需要时间，慢慢累积，成为高手只是时间问题。），不希望大家是Paper OCP!
大家有在学习OCP或在Oracle入门时找不到方向的可以找我。
