678.Which are the two prerequisites before setting up Flashback Data Archive? (Choose two.)
A.Flash recovery area must be defined
B.Undo retention guarantee must be enabled.
C.Database must be running in archivelog mode.
D.Automatic undo management must be enabled.
E.The tablespace in which the Flashback Data Archive is created must have automatic segment space
Management (ASSM).
Answer: DE
答案解析：
闪回数据归档参考：http://blog.csdn.net/rlhua/article/details/12221269
A,错误，闪回数据归档跟FRA区没有关系，闪回归档的数据是保存在闪回数据表空间的数据文件里。
B,错误，参考http://blog.csdn.net/rlhua/article/details/12222819，闪回数据归档和undo数据没关系。
C,错误，在非归档模式下也能创建闪回数据归档。
sys@TEST0924> archive log list
Database log mode No Archive Mode
Automatic archival Disabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 16
Current log sequence 20
sys@TEST0924> create flashback archive fla1 tablespace users quota 10M retention 1 year;
Flashback archive created.
D,正确，必须是自动还原管理
自动管理下能创建成功，切换到手动管理后，创建失败。
sys@TEST0924> show parameter undo
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
undo_management string AUTO
undo_retention integer 900
undo_tablespace string UNDOTBS1
sys@TEST0924> create flashback archive fla1 tablespace users quota 10M retention 1 year;
Flashback archive created.
sys@TEST0924> alter system set undo_management=manual scope=spfile;
System altered.
sys@TEST0924> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
sys@TEST0924> startup
ORACLE instance started.
Total System Global Area 3340451840 bytes
Fixed Size 2232960 bytes
Variable Size 3204451712 bytes
Database Buffers 117440512 bytes
Redo Buffers 16326656 bytes
Database mounted.
Database opened.
sys@TEST0924> show parameter undo
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
undo_management string MANUAL
undo_retention integer 900
undo_tablespace string UNDOTBS1
sys@TEST0924> create flashback archive fla2 tablespace users quota 10M retention 1 year;
create flashback archive fla2 tablespace users quota 10M retention 1 year
*
ERROR at line 1:
ORA-55628: Flashback Archive supports Oracle 11g or higher
E，正确。TESTUNDOTBS 为手动管理的，在此上面创建闪回数据归档，报错。所以必须在ASSM表空间下使用
sys@TEST0924> select tablespace_name,segment_space_management from dba_tablespaces;
TABLESPACE_NAME SEGMEN
------------------------------ ------
SYSTEM MANUAL
SYSAUX AUTO
UNDOTBS1 MANUAL
TEMP MANUAL
USERS AUTO
EXAMPLE AUTO
TESTTBS AUTO
TESTUNDOTBS MANUAL
8 rows selected.
sys@TEST0924> create flashback archive fla2 tablespace users quota 10M retention 1 year
2
sys@TEST0924> create flashback archive fla2 tablespace TESTUNDOTBS quota 10M retention 1 year;
create flashback archive fla2 tablespace TESTUNDOTBS quota 10M retention 1 year
*
ERROR at line 1:
ORA-55627: Flashback Archive tablespace must be ASSM tablespace