Oracle 11g Flashback Data Archive(闪回数据归档)
UNDO表空间记录的回滚信息虽然可以提供回闪查询,但时间久了,这些信息会被覆盖掉,其实只要事务一提交,他们就变成可覆盖的对象了,所
Flashback Data Archive(闪回数据归档)
UNDO表空间记录的回滚信息虽然可以提供回闪查询,但时间久了,这些信息会被覆盖掉,其实只要事务一提交,他们就变成可覆盖的对象了,所以经常在做回闪查询时,我们会因为找不到undo block而收到1555错误,11G里面引入了Flashback Data Archive ,他用于存储数据的所有改变,时间由你自己设定,消耗的是更多的磁盘空间,现在来看下这个特性。
一、创建闪回数据归档
1、为了创建闪回数据归档,必须拥有DBA角色或拥有系统权限flashback archive administer。
sys@MYDB> select * from dba_sys_privs where privilege like '%FLASH%';
GRANTEE PRIVILEGE ADM
------------------------------ ---------------------------------------- ---
SYS FLASHBACK ANY TABLE NO
DBA FLASHBACK ANY TABLE YES
SYS FLASHBACK ARCHIVE ADMINISTER NO
DBA FLASHBACK ARCHIVE ADMINISTER YES
sys@MYDB> grant flashback archive administer to gyj;
Grant succeeded.
2、创建表空间
sys@MYDB> create tablespace flash_tbs1 datafile '/u01/app/Oracle/oradata/mydb/flash_tbs1.dbf' size 20480M;
Tablespace created.
3、创建闪回归档
sys@MYDB> create flashback archive flash1 tablespace flash_tbs1 quota 1024M retention 5 year;
Flashback archive created.
二、更改闪回数据归档
sys@MYDB> alter flashback archive flash1 set default;
Flashback archive altered.
sys@MYDB> alter flashback archive flash1 add tablespace tp1; --添加表空间
Flashback archive altered.
sys@MYDB> alter flashback archive flash1 remove tablespace tp1;--删除表空间
Flashback archive altered.
sys@MYDB> alter flashback archive flash1 modify tablespace flash_tbs1 quota 2048M;--添加配额
Flashback archive altered.
sys@MYDB> alter flashback archive flash1 modify retention 3 year;
Flashback archive altered.
sys@MYDB> alter flashback archive flash1 purge all; -- 清除所有
Flashback archive altered.
sys@MYDB> alter flashback archive flash1 purge before timestamp (systimestamp - interval '2' day);--清除2天前的
Flashback archive altered.
sys@MYDB> alter flashback archive flash1 purge before scn 123344;
Flashback archive altered.
三、启用和禁用闪回数据归档
1、在建表的同时就启用表的闪回日志
gyj@MYDB> create table t1(id int,name varchar2(10)) flashback archive flash1;
Table created.
2、也可以在建表后,再启用表的闪回日志
alter table t1 flashback archive;--为表启用闪回数据归档,没指定表示使用数据库默认的
alter table t1 flashback archive flash1; ;--为表启用闪回数据归档,指定在特定的闪回数据归档中存储表的变化
3、数据库将把T1表的数据归档到默认的闪回数据归档中
gyj@MYDB> select * from dba_flashback_archive_tables;
TABLE_NAME OWNER_NAME FLASHBACK_ARCHIVE_NAME ARCHIVE_TABLE_NAME STATUS
----------- ----------- ---------------------- ---------------- -------------
T1 GYJ FLASH1 SYS_FBA_HIST_17877 ENABLED
4、在使用闪回数据归档前,,必须设置默认闪回数据归档
gyj@MYDB> select flashback_archive_name,status from dba_flashback_archive;
FLASHBACK_ARCHIVE_NAME STATUS ------------------------------------
FLASH1 DEFAULT
5、禁用闪回数据归档
gyj@MYDB> alter table t1 no flashback archive;
Table altered.

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