使用bbed不僅僅可以找回已經delete的數據還可以恢復update的數據，當然過程要比恢復delete的數據復雜一些。
實驗過程如下：
SYS@ORCL>create table bbed_test(x int,y varchar2(20));
Table created.
SYS@ORCL>insert into bbed_test values(1,'BADLY9');
1 row created.
SYS@ORCL>insert into bbed_test values(2,'JP');
1 row created.
SYS@ORCL>commit;
Commit complete.
SYS@ORCL>select rowid, dbms_rowid.rowid_relative_fno(rowid)rel_fno,
2 dbms_rowid.rowid_block_number(rowid)blockno,
3 dbms_rowid.rowid_row_number(rowid) rowno
4 from bbed_test;
ROWID REL_FNO BLOCKNO ROWNO
------------------ ---------- ---------- ----------
AAAM0WAABAAAOuCAAA 1 60290 0
AAAM0WAABAAAOuCAAB 1 60290 1
SYS@ORCL>update bbed_test set y='JP1' where x=1;
1 row updated.
SYS@ORCL>commit;
Commit complete.
SYS@ORCL>select dump(1,'16') from dual;
DUMP(1,'16')
-----------------
Typ=2 Len=2: c1,2
SYS@ORCL>select dump(2,'16') from dual;
DUMP(2,'16')
-----------------
Typ=2 Len=2: c1,3
SYS@ORCL>select dump('BADLY9',16) from dual;
DUMP('BADLY9',16)
-------------------------------
Typ=96 Len=6: 42,41,44,4c,59,39
SYS@ORCL>select dump('JP1','16') from dual;
DUMP('JP1','16')
----------------------
Typ=96 Len=3: 4a,50,31
SYS@ORCL>select * from bbed_test;
X Y
---------- --------------------
1 JP1
2 JP
下面使用bbed進行查看
BBED> set dba 1,60290
DBA 0x0040eb82 (4254594 1,60290)
BBED> map
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Dba:0x0040eb82
------------------------------------------------------------
KTB Data Block (Table/Cluster)
struct kcbh, 20 bytes @0
struct ktbbh, 72 bytes @20
struct kdbh, 14 bytes @92
struct kdbt[1], 4 bytes @106
sb2 kdbr[2] @110
ub1 freespace[8042] @114
ub1 rowdata[32] @8156
ub4 tailchk @8188
BBED> p kdbr
sb2 kdbr[0] @110 8064
sb2 kdbr[1] @112 8074
BBED> p *kdbr[1]
rowdata[10]
-----------
ub1 rowdata[10] @8166 0x2c
8166-8074=92
BBED> x /rnc
rowdata[10] @8166
-----------
flag@8166: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8167: 0x00
cols@8168: 2
col 0[2] @8169: 2
col 1[2] @8172: JP
BBED> p *kdbr[0]
rowdata[0]
----------
ub1 rowdata[0] @8156 0x2c
BBED> x /rnc
rowdata[0] @8156
----------
flag@8156: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8157: 0x02
cols@8158: 2
col 0[2] @8159: 1
col 1[3] @8162: JP1
BBED> set count 64
COUNT 64
BBED> d /v
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Offsets: 8156 to 8191 Dba:0x0040eb82
-------------------------------------------------------
2c020202 c102034a 50312c00 0202c103 l ,...?..JP1,...?.
024a502c 000202c1 02064241 444c5939 l .JP,...?..BADLY9
0206d5a3 l ..?
<16 bytes per line>
使用bbed找回歷史值
通過dump出來的值，推算出來第一條記錄的起點02c1 02064241 444c5939
在這個值的基礎上offset-3得到offset的值為8175
8175-92=8083 1f93
BBED> p kdbr
sb2 kdbr[0] @110 8064
sb2 kdbr[1] @112 8074
--修改row directory指針位置
BBED> m /x 931f
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Offsets: 110 to 173 Dba:0x0040eb82
------------------------------------------------------------------------
931f8a1f 02000000 02000200 791f321f 831e481e 00000000 00000000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
<32 bytes per line>
BBED> p kdbr
sb2 kdbr[0] @110 8083
sb2 kdbr[1] @112 8074
BBED> sum apply
Check value for File 1, Block 60290:
current = 0x3e20, required = 0x3e20
BBED> verify
DBVERIFY - Verification starting
FILE = /u01/app/oracle/oradata/ORCL/system01.dbf
BLOCK = 60290
Block Checking: DBA = 4254594, Block Type = KTB-managed data block
data header at 0x79a25c
kdbchk: xaction header lock count mismatch
trans=2 ilk=1 nlo=0 --提示事務錯誤
Block 60290 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
BBED> p *kdbr[0]
rowdata[19]
-----------
ub1 rowdata[19] @8175 0x2c
BBED> d
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Offsets: 8175 to 8191 Dba:0x0040eb82
------------------------------------------------------------------------
2c000202 c1020642 41444c59 390206d5 a3
<32 bytes per line>
BBED> x /rnc
rowdata[19] @8175
-----------
flag@8175: 0x2c (KDRHFL, KDRHFF, KDRHFH)
lock@8176: 0x00 --被更新前的記錄事務鎖標識為0，而更新後的事務鎖標識為2
cols@8177: 2
col 0[2] @8178: 1
col 1[6] @8181: BADLY9
--修改事務鎖標識為2
BBED> m /x 02 offset +1
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Offsets: 8176 to 8191 Dba:0x0040eb82
------------------------------------------------------------------------
020202c1 02064241 444c5939 0206d5a3
<32 bytes per line>
--把更新後值得事務鎖標識改為0
BBED> set offset 8156
OFFSET 8156
BBED> m /x 00 offset +1
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Offsets: 8157 to 8191 Dba:0x0040eb82
------------------------------------------------------------------------
000202c1 02034a50 312c0002 02c10302 4a502c02 0202c102 06424144 4c593902
06d5a3
<32 bytes per line>
BBED> sum apply
Check value for File 1, Block 60290:
current = 0x3c22, required = 0x3c22
BBED> verify
DBVERIFY - Verification starting
FILE = /u01/app/oracle/oradata/ORCL/system01.dbf
BLOCK = 60290
Block Checking: DBA = 4254594, Block Type = KTB-managed data block
data header at 0x28225c
kdbchk: the amount of space used is not equal to block size
used=44 fsc=3 avsp=8052 dtl=8096 --提示塊的空間使用不正確
Block 60290 failed with check code 6110
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
此時要將所有itl的fsc全部改為0，然後將kdbh.kdbhavsp和kdbh.kdbhtosp的值改成相等，它們的值都等於dbv校驗中顯示的dtl－used。本次案例為8096-44 741f
BBED> p ktbbh
struct ktbbh, 72 bytes @20
ub1 ktbbhtyp @20 0x01 (KDDBTDATA)
union ktbbhsid, 4 bytes @24
ub4 ktbbhsg1 @24 0x0000cd16
ub4 ktbbhod1 @24 0x0000cd16
struct ktbbhcsc, 8 bytes @28
ub4 kscnbas @28 0x0007a3d3
ub2 kscnwrp @32 0x0000
b2 ktbbhict @36 7938
ub1 ktbbhflg @38 0x03 (KTBFONFL)
ub1 ktbbhfsl @39 0x00
ub4 ktbbhfnx @40 0x00000000
struct ktbbhitl[0], 24 bytes @44
struct ktbitxid, 8 bytes @44
ub2 kxidusn @44 0x0008
ub2 kxidslt @46 0x0009
ub4 kxidsqn @48 0x0000010e
struct ktbituba, 8 bytes @52
ub4 kubadba @52 0x00800270
ub2 kubaseq @56 0x00c4
ub1 kubarec @58 0x02
ub2 ktbitflg @60 0x8000 (KTBFCOM)
union _ktbitun, 2 bytes @62
b2 _ktbitfsc @62 0
ub2 _ktbitwrp @62 0x0000
ub4 ktbitbas @64 0x0007a37e
struct ktbbhitl[1], 24 bytes @68
struct ktbitxid, 8 bytes @68
ub2 kxidusn @68 0x0001
ub2 kxidslt @70 0x0024
ub4 kxidsqn @72 0x000000d5
struct ktbituba, 8 bytes @76
ub4 kubadba @76 0x008000d8
ub2 kubaseq @80 0x0082
ub1 kubarec @82 0x38
ub2 ktbitflg @84 0x2001 (KTBFUPB)
union _ktbitun, 2 bytes @86
b2 _ktbitfsc @86 3
ub2 _ktbitwrp @86 0x0003
ub4 ktbitbas @88 0x0007a3d5
BBED> m /x 00 offset 86
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Offsets: 86 to 149 Dba:0x0040eb82
------------------------------------------------------------------------
0000d5a3 07000001 0200ffff 1600801f 741f771f 00000200 931f8a1f 02000000
02000200 791f321f 831e481e 00000000 00000000 00000000 00000000 00000000
<32 bytes per line>
BBED> sum apply
Check value for File 1, Block 60290:
current = 0x3c21, required = 0x3c21
BBED> p kdbh
struct kdbh, 14 bytes @92
ub1 kdbhflag @92 0x00 (NONE)
b1 kdbhntab @93 1
b2 kdbhnrow @94 2
sb2 kdbhfrre @96 -1
sb2 kdbhfsbo @98 22
sb2 kdbhfseo @100 8064
b2 kdbhavsp @102 8052
b2 kdbhtosp @104 8055
BBED> m /x 741f offset 102
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Offsets: 102 to 165 Dba:0x0040eb82
------------------------------------------------------------------------
741f771f 00000200 931f8a1f 02000000 02000200 791f321f 831e481e 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
<32 bytes per line>
BBED> m /x 741f offset 104
File: /u01/app/oracle/oradata/ORCL/system01.dbf (1)
Block: 60290 Offsets: 104 to 167 Dba:0x0040eb82
------------------------------------------------------------------------
741f0000 0200931f 8a1f0200 00000200 0200791f 321f831e 481e0000 00000000
00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
<32 bytes per line>
BBED> sum apply
Check value for File 1, Block 60290:
current = 0x3c22, required = 0x3c22
BBED> verify
DBVERIFY - Verification starting
FILE = /u01/app/oracle/oradata/ORCL/system01.dbf
BLOCK = 60290
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
此時數據塊驗證通過
現在回到庫裡進行驗證：
SYS@ORCL>alter system flush buffer_cache;
System altered.
SYS@ORCL>select * from bbed_test;
X Y
---------- --------------------
1 BADLY9
2 JP
可以看到UPDATE之前的數據已經被恢復回來了。
實驗過程參考飛總的文章：
http;//www.xifenfei.com/3704.html
