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。
一丶创建闪回数据归档
1丶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丶创建表空间
sys@MYDB> create tablespace flash_tbs1 datafile \'/u01/app/oracle/oradata/mydb/flash_tbs1.dbf\' size 20480M;
Tablespace created.
3丶创建闪回归档
sys@MYDB> create flashback archive flash1 tablespace flash_tbs1 quota 1024M retention 5 year;
Flashback archive created.
二丶更改闪回数据归档
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.
三丶启用和禁用闪回数据归档
1丶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丶也可以在建表后，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丶数据库将把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丶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丶禁用闪回数据归档
gyj@MYDB> alter table t1 no flashback archive;
Table altered.
四丶闪回数据归档的限制
在使用闪回归档的过程中有某些限制。对于已经启用闪回的表，不能使用DDL命令drop column（11r2可以drop column）,但可以add column命令。删除属于一个启用了闪回数据归档的表列的唯一方法是首先关闭闪回归档功能。但是，这样会删除所有闪回归档数据。
1丶ALTER TABLE：
Drops, renames, or modifies a column (11GR2是可以的)
Performs partition or subpartition operations
Converts a LONG column to a LOB column
Includes an UPGRADE TABLE clause, with or without an INCLUDING DATA clause
2丶 DROP TABLE
3丶TRUNCATE TABLE (11GR2是可以的)
4丶RENAME TABLE (11GR2也是可以的)
gyj@MYDB> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
gyj@MYDB> alter table t1 drop column name;
Table altered.
gyj@MYDB> alter table t1 add(name varchar2(100));
Table altered.
gyj@MYDB> alter table t1 rename to t10;
Table altered.
gyj@MYDB> truncate table t10;
Table truncated.
gyj@MYDB> drop table t10;
drop table t10
*
ERROR at line 1:
ORA-55610: Invalid DDL statement on history-tracked table
gyj@MYDB> alter table t10 no flashback archive;
Table altered.
gyj@MYDB> drop table t10;
Table dropped.
五丶监控认回数据归档
1丶查哪些表已经启用了闪回数据归档
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
2丶查数据库中所有的闪回数据归档
gyj@MYDB> select flashback_archive_name,retention_in_days from dba_flashback_archive;
FLASHBACK_ARCHIVE_NAME RETENTION_IN_DAYS
-------------------------------------------------- -----------------
FLASH1 1095
3丶查有关闪回数据归档所使用的表空间的信息
gyj@MYDB> select flashback_archive_name,tablespace_name,quota_in_mb from dba_flashback_archive_ts;
FLASHBACK_ARCHIVE_NAME TABLESPACE_NAME QUOTA_IN_MB
---------------------------- ----------------------- -----------------
FLASH1 FLASH_TBS1 2048
六丶使用闪回数据归档：例子
gyj@MYDB> create table test_gyj (id int,name varchar2(10));
Table created.
gyj@MYDB> alter table test_gyj flashback archive flash1;
Table altered.
gyj@MYDB> begin
2 for i in 1 .. 100 loop
3 insert into test_gyj values(i,\'gyj\'||i);
4 commit;
5 end loop;
6 end;
7 /
PL/SQL procedure successfully completed.
gyj@MYDB> select count(*) from test_gyj;
COUNT(*)
----------
100
gyj@MYDB> col FLASHBACK_ARCHIVE_NAME for a10
gyj@MYDB> col TABLE_NAME for a10
gyj@MYDB> col ARCHIVE_TABLE_NAME for a20
gyj@MYDB> col OWNER_NAME for a5
gyj@MYDB> select * from dba_flashback_archive_tables;
TABLE_NAME OWNER FLASHBACK_ ARCHIVE_TABLE_NAME STATUS
---------- ----- ---------- -------------------- -------------
T1 GYJ FLASH1 SYS_FBA_HIST_17890 ENABLED
T10 GYJ FLASH1 SYS_FBA_HIST_17898 ENABLED
TEST_GYJ GYJ FLASH1 SYS_FBA_HIST_17908 ENABLED
gyj@MYDB> select count(*) from SYS_FBA_HIST_17908;
COUNT(*)
----------
0
gyj@MYDB> select current_scn from v$database;
CURRENT_SCN
-----------
2353743
gyj@MYDB> delete from test_gyj;
100 rows deleted.
gyj@MYDB> commit;
Commit complete.
gyj@MYDB> select current_scn from v$database;
CURRENT_SCN
-----------
2353790
gyj@MYDB> select count(*) from test_gyj as of scn 2353743;
COUNT(*)
----------
100
gyj@MYDB> select count(*) from test_gyj as of scn 2353790;
COUNT(*)
----------
0
gyj@MYDB> select count(*) from SYS_FBA_HIST_17908;
COUNT(*)
----------
0
gyj@MYDB> select count(*) from SYS_FBA_HIST_17908;--刷新数据有缓慢，耐心等待！！！
COUNT(*)
----------
200
七丶删除闪回归档数据
drop flashback archive flash1;
未完！！！继续更新中。。。。。。。。。。。。。。。。。。
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