Flashback Database：
案例分析：
flashback database：利用flashback log 对整个database 做回退到过去的某个时间点（用于DDL 的误操作如drop 和 truncate），类似于RMAN的不完全恢复（media recovery incompelete）
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因为flashback database是不完全恢复，在恢复到过去的时间点前应该对数据库备份！
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1
、查看flashback database是否开启
07
:
21
:
27
SQL> select flashback_on
from
v$database;
FLASHBACK_ON
------------------
NO
2
、创建recovery area
07
:
21
:
33
SQL> show parameter recover
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string /u01/app/oracle/flash_recovery
_area
db_recovery_file_dest_size big integer 2G
recovery_parallelism integer
2
---recovery area可以存储flashback log、archive log、rman backup等
[oracle@work ~]$ mkdir -p /disk1/recovery/prod
配置recovery area：
07
:
22
:
49
SQL> alter system set db_recovery_file_dest=
'/disk1/recovery/prod'
scope=spfile;
System altered.
在归档模式下启用flashback database：
07
:
25
:
06
SQL> alter database flashback
on
;
Database altered.
07
:
25
:
29
SQL> select flashback_on
from
v$database;
FLASHBACK_ON
------------------
YES
07
:
25
:
38
SQL> alter database open;
Database altered.
案例
1
：flashback database恢复DDL误操作（基于SCN)
flashback database可以用于基于时间点或SCN的数据恢复（可以通过logminer来查看DDL操作的时间点）
1
)模拟环境
15
:
18
:
17
SYS@ test1 >select current_scn
from
v$database;
CURRENT_SCN
-----------
1264788
07
:
26
:
30
SQL> select *
from
test;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7369
SMITH CLERK
7902
17
-DEC
-80
800
20
7499
ALLEN SALESMAN
7698
20
-FEB
-81
1600
300
30
7369
SMITH CLERK
7902
17
-DEC
-80
800
20
7499
ALLEN SALESMAN
7698
20
-FEB
-81
1600
300
30
7521
WARD SALESMAN
7698
22
-FEB
-81
1250
500
30
7566
JONES MANAGER
7839
02
-APR
-81
2975
20
7654
MARTIN SALESMAN
7698
28
-SEP
-81
1250
1400
30
7698
BLAKE MANAGER
7839
01
-MAY
-81
2850
30
7782
CLARK MANAGER
7839
09
-JUN
-81
2450
10
7788
SCOTT ANALYST
7566
19
-APR
-87
3000
20
7839
KING PRESIDENT
17
-NOV
-81
5000
10
7844
TURNER SALESMAN
7698
08
-SEP
-81
1500
0
30
7876
ADAMS CLERK
7788
23
-MAY
-87
1100
20
7900
JAMES CLERK
7698
03
-DEC
-81
950
30
7902
FORD ANALYST
7566
03
-DEC
-81
3000
20
7934
MILLER CLERK
7782
23
-JAN
-82
1300
10
16
rows selected.
07
:
26
:
36
SQL> drop table test purge;
Table dropped.
07
:
27
:
20
SQL> create table test
as
select *
from
emp
where
rownum=
1
;
Table created.
07
:
27
:
25
SQL> select *
from
test;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7369
SMITH CLERK
7902
17
-DEC
-80
800
20
查看flashback 日志：
[oracle@work ~]$ ls /disk1/recovery/prod/PROD/flashback/
o1_mf_74q999lb_.flb
关闭数据库后，在mount状态下恢复：
07
:
29
:
22
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
07
:
29
:
53
SQL> startup mount
ORACLE instance started.
Total System Global Area
314572800
bytes
Fixed Size
1219184
bytes
Variable Size
71304592
bytes
Database Buffers
239075328
bytes
Redo Buffers
2973696
bytes
Database mounted.
通过flashback database将库恢复到过去的scn：
07
:
30
:
02
SQL> flashback database to scn
1264788
;
Flashback complete.
将database以read only方式打开，先验证下恢复是否成功，如果不成功，再从新进入mount下恢复
07
:
31
:
29
SQL> alter database open read only;
Database altered.
07
:
31
:
34
SQL> select *
from
scott.test;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7369
SMITH CLERK
7902
17
-DEC
-80
800
20
7499
ALLEN SALESMAN
7698
20
-FEB
-81
1600
300
30
7369
SMITH CLERK
7902
17
-DEC
-80
800
20
7499
ALLEN SALESMAN
7698
20
-FEB
-81
1600
300
30
7521
WARD SALESMAN
7698
22
-FEB
-81
1250
500
30
7566
JONES MANAGER
7839
02
-APR
-81
2975
20
7654
MARTIN SALESMAN
7698
28
-SEP
-81
1250
1400
30
7698
BLAKE MANAGER
7839
01
-MAY
-81
2850
30
7782
CLARK MANAGER
7839
09
-JUN
-81
2450
10
7788
SCOTT ANALYST
7566
19
-APR
-87
3000
20
7839
KING PRESIDENT
17
-NOV
-81
5000
10
7844
TURNER SALESMAN
7698
08
-SEP
-81
1500
0
30
7876
ADAMS CLERK
7788
23
-MAY
-87
1100
20
7900
JAMES CLERK
7698
03
-DEC
-81
950
30
7902
FORD ANALYST
7566
03
-DEC
-81
3000
20
7934
MILLER CLERK
7782
23
-JAN
-82
1300
10
16
rows selected.
--恢复成功，重新以resetlogs的方式open database
07
:
31
:
40
SQL> shutdown immedaite
SP2
-0717
: illegal SHUTDOWN option
07
:
31
:
45
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
07
:
32
:
02
SQL> startup mount
ORACLE instance started.
Total System Global Area
314572800
bytes
Fixed Size
1219184
bytes
Variable Size
71304592
bytes
Database Buffers
239075328
bytes
Redo Buffers
2973696
bytes
Database mounted.
07
:
32
:
10
SQL> alter database open resetlogs;
Database altered.
验证：
07
:
32
:
25
SQL> select *
from
scott.test;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- ---------- --------- ---------- --------- ---------- ---------- ----------
7369
SMITH CLERK
7902
17
-DEC
-80
800
20
7499
ALLEN SALESMAN
7698
20
-FEB
-81
1600
300
30
7369
SMITH CLERK
7902
17
-DEC
-80
800
20
7499
ALLEN SALESMAN
7698
20
-FEB
-81
1600
300
30
7521
WARD SALESMAN
7698
22
-FEB
-81
1250
500
30
7566
JONES MANAGER
7839
02
-APR
-81
2975
20
7654
MARTIN SALESMAN
7698
28
-SEP
-81
1250
1400
30
7698
BLAKE MANAGER
7839
01
-MAY
-81
2850
30
7782
CLARK MANAGER
7839
09
-JUN
-81
2450
10
7788
SCOTT ANALYST
7566
19
-APR
-87
3000
20
7839
KING PRESIDENT
17
-NOV
-81
5000
10
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