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
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.
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！
案例
2
：基于timestamp的flashback database
04
:
04
:
28
SQL> show user;
USER is
"SYS"
04
:
08
:
04
SQL> conn scott/tiger
Connected.
04
:
08
:
13
SQL> select to_char(sysdate,
'yyyy-mm-dd hh24:mi:ss'
)
from
dual;
TO_CHAR(SYSDATE,'YY
-------------------
2011
-03
-18
04
:
08
:
42
04
:
09
:
02
SQL> conn /
as
sysdba
Connected.
04
:
09
:
07
SQL> select current_scn
from
v$database;
CURRENT_SCN
-----------
1437597
04
:
09
:
10
SQL> conn scott/tiger
Connected.
04
:
09
:
29
SQL> select *
from
tab;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
EMP TABLE
DEPT TABLE
BONUS TABLE
SALGRADE TABLE
QUEST_SL_TEMP_EXPLAIN1 TABLE
EMP1 TABLE
ERRLOG TABLE
PART_SALES TABLE
T01 TABLE
DEPT1 TABLE
10
rows selected.
select *
from
t01;
ID NA
---------- --
1
TM
04
:
10
:
07
SQL>
insert
into
t01 values(
2
,
'aa'
);
1
row created.
04
:
10
:
17
SQL>
insert
into
t01 values(
3
,
'bb'
);
1
row created.
04
:
10
:
26
SQL> commit;
Commit complete.
04
:
10
:
30
SQL> drop table t01;
Table dropped.
04
:
10
:
59
SQL> conn /
as
sysdba
Connected.
04
:
11
:
03
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
04
:
11
:
28
SQL> startup mount
ORACLE instance started.
Total System Global Area
314572800
bytes
Fixed Size
1219184
bytes
Variable Size
184550800
bytes
Database Buffers
125829120
bytes
Redo Buffers
2973696
bytes
Database mounted.
将database恢复到过去的时间点：
04
:
12
:
07
SQL> flashback database to timestamp to_timestamp(
'2011-03-18 04:10:26'
,
'yyyy-mm-dd hh24:mi:ss'
);
Flashback complete.
04
:
13
:
34
SQL> alter database open;
alter database open
*
ERROR
at
line
1
:
ORA
-01589
: must use RESETLOGS
or
NORESETLOGS option
for
database open
04
:
14
:
10
SQL> alter database open noresetlogs;
alter database open noresetlogs
*
ERROR
at
line
1
:
ORA
-01610
: recovery using the BACKUP CONTROLFILE option must be done
04
:
14
:
18
SQL> alter database open resetlogs;
Database altered.
04
:
15
:
35
SQL> select *
from
v$log;
GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIME
---------- ---------- ---------- ---------- ---------- --- ---------------- ------------- -------------------
1
1
0
52428800
2
YES UNUSED
0
2
1
0
52428800
2
YES UNUSED
0
3
1
0
52428800
2
YES UNUSED
0
4
1
0
52428800
2
YES UNUSED
0
5
1
0
52428800
2
YES UNUSED
0
6
1
1
52428800
2
NO CURRENT
1437637
2011
-03
-18
04
:
14
:
27
6
rows selected.
04
:
15
:
59
SQL> conn scott/tiger
Connected.
04
:
16
:
18
SQL> select *
from
t01;
ID NA
---------- --
1
TM
04
:
34
:
35
SQL> desc v$flashback_database_log;
Name Null? Type
----------------------------------------------------------------------------------- -------- - OLDEST_FLASHBACK_SCN NUMBER
OLDEST_FLASHBACK_TIME DATE
RETENTION_TARGET NUMBER
FLASHBACK_SIZE NUMBER
ESTIMATED_FLASHBACK_SIZE NUMBER
04
:
34
:
37
SQL> select *
from
v$flashback_database_log;
OLDEST_FLASHBACK_SCN OLDEST_FLASHBACK_TI RETENTION_TARGET FLASHBACK_SIZE TIMATED_FLASHBACK_SIZE
-------------------- ------------------- ---------------- -------------- ----------------------
1436931
2011
-03
-18
03
:
51
:
43
1440
8192000
115703808
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[oracle@rh6 ~]$ sqlplus
'/as sysdba'
SQL*Plus: Release
11.2.
0.1.
0
Production
on
Thu Jan
15
11
:
38
:
34
2015
Copyright (c)
1982
,
2009
, Oracle. All rights reserved.
Connected to an idle instance.
11
:
41
:
52
SYS@ test1 >select name,FLASHBACK_ON
from
v$database;
NAME FLASHBACK_ON
--------- ------------------
TEST1 YES
Elapsed:
00
:
00
:
00.00
11
:
38
:
34
SYS@ test1 >startup
ORACLE instance started.
Total System Global Area
523108352
bytes
Fixed Size
1337632
bytes
Variable Size
188745440
bytes
Database Buffers
327155712
bytes
Redo Buffers
5869568
bytes
Database mounted.
Database opened.
--下面查看闪回区分配的大小为大约M，闪回分钟以内的数据则需要M左右的空间
--注意列oldest_flashback_time说明了允许返回的最早的时间点
11
:
39
:
17
SYS@ test1 >select oldest_flashback_scn old_flhbck_scn,oldest_flashback_time old_flhbck_tim,
11
:
39
:
37
2
retention_target rete_trgt,flashback_size/
1024
/
1024
flhbck_siz,
11
:
39
:
47
3
estimated_flashback_size/
1024
/
1024
est_flhbck_size
11
:
40
:
01
4
from
v$flashback_database_log;
OLD_FLHBCK_SCN OLD_FLHBCK_T RETE_TRGT FLHBCK_SIZ EST_FLHBCK_SIZE
-------------- ------------ ---------- ---------- ---------------
11898580
10
-JAN
-15
1440
305.429688
266.601563
--查看闪回
11
:
40
:
15
SYS@ test1 >select *
from
v$flashback_database_stat;
BEGIN_TIME END_TIME FLASHBACK_DATA DB_DATA REDO_DATA ESTIMATED_FLASHBACK_SIZE
------------ ------------ -------------- ---------- ---------- ------------------------
15
-JAN
-15
15
-JAN
-15
573440
24576
109056
0
--查看sga中分配的闪回空间大小
11
:
40
:
45
SYS@ test1 >select *
from
v$sgastat
where
name like
'flashback%'
;
POOL NAME BYTES
------------ -------------------------- ----------
shared pool flashback generation buff
4149140
shared pool flashback_marker_cache_si
9196
|
本文转自 客居天涯 51CTO博客，原文链接：http://blog.51cto.com/tiany/1604018，如需转载请自行联系原作者
