Oracle11g新特性：Flashback Data Archive续

参考文章:http://www.ningoo.net/html/2007/oracle11g_new_feature_flashback_data_archive2.html

一.后台进程

Oracle11g为Flashback data archive特性专门引入了一个新的后台进程FBDA，用于将追踪表(traced table，也就是将指定使用flashback data archive的table)的历史变化数据转存到闪回归档区。

NING@11g>select name,description from v$bgprocess where name=’FBDA’;
NAME DESCRIPTION
—————————— —————————————-
FBDA Flashback Data Archiver Process
二.一些限制条件
1.Flashback data archive只能在ASSM的tablespace上创建

NING@11g>create flashback archive test_archive2
2 tablespace “TEST”
3 quota 1 m
4 retention 1 day;
tablespace “TEST”
*
ERROR at line 2:
ORA-55627: Flashback Archive tablespace must be ASSM tablespace
2.Flashback data archive要求必须使用自动undo管理

NING@11g>show parameter undo_management;
NAME TYPE VALUE
———————————— ———- ——————————
undo_management string MANUAL
NING@11g>create flashback archive test_archive2
2 tablespace “TEST”
3 quota 1 m
4 retention 1 day;
create flashback archive test_archive2
*
ERROR at line 1:
ORA-55628: Flashback Archive supports Oracle 11g or higher
NING@11g>show parameter compatible
NAME TYPE VALUE
———————————— ———- ——————————
compatible string 11.1.0.0.0
三.空间配额
磁盘配额由quota子句指定，只能使用整数，单位可以是M/G/T/P。如果省略quota子句，则默认为unlimited，但这样则要求用户对于该tablespace必须有unlimited的空间配额，并且指定的quota必须小于用户在该tablespace上的配额限制，在我的试验中，只有flasback data archive的配额小于tablespace的配额84M以上才可以创建成功，否则失败，至于为什么会是84M，暂时还不清楚，我的系统是Redhat AS5，有兴趣的朋友请帮忙测试这个问题。昨天昏了头了，应该是该用户在该tablespace中已经占用了80多M的空间，所以会出现这个问题。
一个Flashback data archive可以使用多个tablespace作为存储空间，创建时指定的tablespace为第一个tablespace，后续还可以通过alter flashback archive … add tablespace增加新的tablespace进来，也可以通过later flashback archive … remove tablespace移除某个tablespace（不会物理删除该tablespace）。

SYS@11g>revoke unlimited tablespace from ning;
Revoke succeeded.
SYS@11g>alter user ning quota 85m on users;
User altered.
NING@11g>create flashback archive test_archive2
2 tablespace “USERS”
3 retention 1 day;
tablespace “USERS”
*
ERROR at line 2:
ORA-55621: User quota on tablespace “USERS” is not enough for Flashback Archive
NING@11g>create flashback archive test_archive2
2 tablespace “USERS”
3 quota 2 m
4 retention 1 day;
tablespace “USERS”
*
ERROR at line 2:
ORA-55621: User quota on tablespace “USERS” is not enough for Flashback Archive
NING@11g>create flashback archive test_archive2
2 tablespace “USERS”
3 quota 1 m
4 retention 1 day;
Operation 218 succeeded.
但是空间配额可以超过该tablespace本身的物理大小

SYS@11g>drop tablespace test including contents and datafiles;
Tablespace dropped.
SYS@11g>create tablespace test
2 datafile ‘/oracle/oradata/ning/test01.dbf’ size 10m;
Tablespace created.
SYS@11g>alter user ning quota unlimited on test;
User altered.
NING@11g>create flashback archive test_archive3
2 tablespace “TEST”
3 quota 100 m
4 retention 1 month;
Operation 218 succeeded.
四.空间不足会导致追踪表上的DML操作失败

NING@11g>create table test as select * from all_objects where 1=2;
Table created.
NING@11g>alter table test flashback archive test_archive1;
Table altered.
NING@11g>insert into test select * from all_objects;
11873 rows created.
NING@11g>insert into test select * from test;
…
NING@11g>/
379936 rows created.
NING@11g>/
insert into test select * from test
*
ERROR at line 1:
ORA-01536: space quota exceeded for tablespace ‘USERS’
五.清除闪回归档区的数据
1.清除所有数据

NING@11g>alter flashback archive test_archive1 purge all;
Operation 219 succeeded.
2.清除某个时间点，比如一天前的数据

NING@11g>alter flashback archive test_archive1
2 purge before timestamp (systimestamp – interval ’1′ day);
Operation 219 succeeded.
3.清除某个SCN之前的历史数据

NING@11g>alter flashback archive test_archive1
2 purge before scn 8570685767554;
Operation 219 succeeded.
六.置于Flashback data archive中的table的一些限制
追踪表(Tracked table)，也就是指定将历史数据保存到某个flashback data archive中的table，不能执行DDL操作(add column除外)。

NING@11g>drop table test;
drop table test
*
ERROR at line 1:
ORA-55610: Invalid DDL statement on history-tracked table
NING@11g>truncate table test;
truncate table test
*
ERROR at line 1:
ORA-55610: Invalid DDL statement on history-tracked table
NING@11g>alter table test drop column object_id;
alter table test drop column object_id
*
ERROR at line 1:
ORA-55610: Invalid DDL statement on history-tracked table

NING@11g>alter table test add col_test int;
Table altered.
但是可以rename table，这一点和文档上说的不一致

NING@11g>rename test to test1;
Table renamed.
NING@11g>select table_name,flashback_archive_name from dba_flashback_archive_tables;
TABLE_NAME FLASHBACK_ARCHIVE_NAME
—————————— ——————————
TEST1 TEST_ARCHIVE1