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利用BBED恢复UPDATE修改前的值

2023-02-26 12:27:49 时间

实验过程如下：
1、创建表guo_test1

[email protected]> create table guoyJoe_t1(id int,name varchar2(10));   Table created.   [email protected]> insert into guoyJoe_t1 values(1,'guoyJoe');   1 row created.   [email protected]> insert into guoyJoe_t1 values(1,'tom');   1 row created.   [email protected]> COMMIT;   Commit complete.

2、查出这行记录的DBA

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 [email protected]> select name,dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block#,dbms_rowid.rowid_row_number(rowid)    row# from guoyJoe_t1;   NAME            FILE#     BLOCK#       ROW# ---------- ---------- ---------- ---------- guoyJoe             5      20877          0 tom                 5      20877          1 ————————————————

3、刷数据缓存

 [email protected]> alter system flush buffer_cache;   System altered.

4、利用BBED找到这行记录（修改前的值：guoyJoe）

BBED> BBED> set file 5    block 20877         FILE#           5         BLOCK#          20877

–观察行头
BBED> p kdbr
sb2 kdbr[0] @118 8074
sb2 kdbr[1] @120 8064

BBED> p *kdbr[0]

rowdata[10]

ub1 rowdata[10] @8174 0x2c

–观察事务
BBBED> x /rnc

rowdata[10] @8174

[email protected]: 0x2c (KDRHFL, KDRHFF, KDRHFH)
[email protected]: 0x01
[email protected]: 2

col 0[2] @8177: 1
col 1[7] @8180: guoyJoe

—观察空间
BBED> p kdbhavsp
sb2 kdbhavsp @110 8042

BBED> p kdbhtosp
sb2 kdbhtosp @112 8042

5、发生UPDATE语句，把原来的值guoyJoe修改成oracledba

[email protected]> update guoyJoe_t1 set name='oracledba' where name='guoyJoe';   1 row updated.   [email protected]> commit;   Commit complete

6、刷数据缓存

[email protected]> alter system flush buffer_cache;   System altered.

7、利用BBED找到这行被修改后的记录（修改后的值上：oracledba）

 BBED> set file 5    block 20877         FILE#           5         BLOCK#          20877

–观察行头
BBED> p kdbr
sb2 kdbr[0] @118 8048
sb2 kdbr[1] @120 8064

BBED> p *kdbr[0]

rowdata[0]

ub1 rowdata[0] @8148 0x2c

–观察事务
BBED> x /rnc

rowdata[0] @8148

[email protected]: 0x2c (KDRHFL, KDRHFF, KDRHFH)
[email protected]: 0x01
[email protected]: 2

col 0[2] @8151: 1
col 1[9] @8154: oracledba

—观察空间
BBED> p kdbhavsp
sb2 kdbhavsp @110 8040

BBED> p kdbhtosp
sb2 kdbhtosp @112 8040

8、对比修改前与修改后的数据

BBED> d /v offset 8174 count 16  File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)  Block: 20877   Offsets: 8174 to 8189  Dba:0x0140518d -------------------------------------------------------  2c000202 c1020767 756f794a 6f650106 l ,...á..guoyJoe..     BBED> d /v offset 8148 count 16  File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)  Block: 20877   Offsets: 8148 to 8163  Dba:0x0140518d -------------------------------------------------------  2c010202 c102096f 7261636c 65646261 l ,...á..oracledba   9、开始恢复 （1）修改row directory指针位置（@118） --修改前

BBED> p kdbr
sb2 kdbr[0]

                              @118      8074 --修改后                                  @118      8048

BBED> p kdbr
sb2 kdbr[0]
g
[email protected]> select to_char(‘8074′,’xxxxxxxxxxxxxx’) from dual;

TO_CHAR(‘8074’,

       1f8a

[email protected]> select to_char(‘8048′,’xxxxxxxxxxxxxx’) from dual;

TO_CHAR(‘8048’,

       1f70

BBED> d /v offset 118 count 16
File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)

Block: 20877 Offsets: 118 to 133 Dba:0x0140518d

701f801f 00000000 00000000 00000000 l p……………

BBED> modify /x 8a offset 118
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) Y
File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)

Block: 20877 Offsets: 118 to 133 Dba:0x0140518d

8a1f801f 00000000 00000000 00000000

<32 bytes per line>

BBED> sum apply
Check value for File 5, Block 20877:
current = 0x8a00, required = 0x8a00

BBED> verify
DBVERIFY – Verification starting
FILE = /u01/app/oracle/oradata/PROD/tp01.dbf
BLOCK = 20877

Block Checking: DBA = 20992397, Block Type = KTB-managed data block
data header at 0x7f76ff66e264
kdbchk: xaction header lock count mismatch —-事务锁报错

    trans=1 ilk=1 nlo=0

Block 20877 failed with check code 6108

DBVERIFY – Verification complete

Total Blocks Examined : 1
Total Blocks Processed (Data) : 1
Total Blocks Failing (Data) : 1
Total Blocks Processed (Index): 0
Total Blocks Failing (Index): 0
Total Blocks Empty : 0
Total Blocks Marked Corrupt : 0
Total Blocks Influx : 0
Message 531 not found; product=RDBMS; facility=BBED

2）接下来修改事务锁 ---把更新前值的事务锁标记从00改为01

BBBED> x /rnc

rowdata[10] @8174

[email protected]: 0x2c (KDRHFL, KDRHFF, KDRHFH)
[email protected]: 0x01
[email protected]: 2

BBED> d /v offset 8175 count 16
File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)

Block: 20877 Offsets: 8175 to 8190 Dba:0x0140518d

000202c1 02076775 6f794a6f 6501066f l …á..guoyJoe..o

BBED> modify /x 01 offset 8175
File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)

Block: 20861 Offsets: 8175 to 8190 Dba:0x0140517d

010202c1 02076775 6f794a6f 650106ed

 --把更新后值的事务锁标识01改为00

BBED> x /rnc

rowdata[0] @8148

[email protected]: 0x2c (KDRHFL, KDRHFF, KDRHFH)
[email protected]: 0x01
[email protected]: 2

BBED> d /v offset 8149 count 16
File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)

Block: 20877 Offsets: 8149 to 8164 Dba:0x0140518d

010202c1 02096f72 61636c65 6462612c l …á..oracledba,

BBED> modify /x 00 offset 8149
File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)

Block: 20861 Offsets: 8159 to 8174 Dba:0x0140517d

000202c1 02096f72 61636c65 6462612c

BBED> sum apply
Check value for File 5, Block 20877:
current = 0x8a00, required = 0x8a00
BBED> verify
DBVERIFY – Verification starting
FILE = /u01/app/oracle/oradata/PROD/tp01.dbf
BLOCK = 20877

Block Checking: DBA = 20992397, Block Type = KTB-managed data block
data header at 0x7cb464
kdbchk: the amount of space used is not equal to block size

    used=46 fsc=0 avsp=8040 dtl=8088 
 ---提示数据块的空间使用不正确（dtl-used=kdbhavsp=kdbhtosp）        8088-46=8042 与 avsp=8040相关2,也就是说我要恢复到8042        (3)修改空间，把空间修改为6a1f,以dtl-used=kdbhavsp为主

[email protected]> select to_char(‘8042′,’xxxxxxxxxxxxxx’) from dual;

  TO_CHAR('8042',    ---------------        1f6a

BBED> modify /x 6a1f offset 110
File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)

Block: 20877 Offsets: 110 to 125 Dba:0x0140518d

6a1f681f 00000200 8a1f801f 00000000

<32 bytes per line>

BBED> modify /x 6a1f offset 112
File: /u01/app/oracle/oradata/PROD/tp01.dbf (5)

Block: 20877 Offsets: 112 to 127 Dba:0x0140518d

6a1f0000 02008a1f 801f0000 00000000

<32 bytes per line>

BBED> sum apply
Check value for File 5, Block 20877:
current = 0x8a00, required = 0x8a00

BBED> verify
DBVERIFY – Verification starting
FILE = /u01/app/oracle/oradata/PROD/tp01.dbf
BLOCK = 20877

DBVERIFY – Verification complete

Total Blocks Examined : 1
Total Blocks Processed (Data) : 1
Total Blocks Failing (Data) : 0
Total Blocks Processed (Index): 0
Total Blocks Failing (Index): 0
Total Blocks Empty : 0
Total Blocks Marked Corrupt : 0
Total Blocks Influx : 0
Message 531 not found; product=RDBMS; facility=BBED

10、恢复成功（oracledba--->guoyJoe）

[email protected]> alter system flush buffer_cache;

System altered.

[email protected]> select name,dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block#,dbms_rowid.rowid_row_number(rowid) row# from guoyJoe_t1 where id=1;

NAME FILE# BLOCK# ROW#

guoyJoe 5 20877 0
tom 5 20877 1

实际上用BBED恢复UPDATE前的值不难，主要是要了解内部原理和块格式 总结如下：  （1）修改行头  （2）修改事务

利用BBED恢复UPDATE修改前的值

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