使用BBED理解和修改Oracle数据块
1.生成bbed list file文件:
SQL> select file#||' '||name||' '||bytes from v$datafile;
$ vim dbfile.txt
1 /u01/app/oradata/sydb/system01.dbf 754974720
2 /u01/app/oradata/sydb/sysaux01.dbf 587202560
3 /u01/app/oradata/sydb/undotbs01.dbf 429916160
4 /u01/app/oradata/sydb/users01.dbf 13107200
5 /disk2/oradata/sydb/tbs01.dbf 1816133632
6 /disk2/oradata/sydb/tbs02.dbf 119537664
7 /disk2/oradata/sydb/tbs03.dbf 20971520
8 /tmp/tbs_tmp.dbf 10485760
2.生成bbed参数文件:
$ vim bbed.par
mode=edit
listfile= dbfile.txt
blocksize=8192
3.创建测试表和数据:
create table tt1 (id number,name varchar2(30)) tablespace tbs03;
insert into tt1 values(1,'AAAA');
insert into tt1 values(2,'BBBB');
commit;
4.查询表数据行所在的数据块号:
select
dbms_rowid.rowid_block_number(rowid) blocknum,
dbms_rowid.ROWID_RELATIVE_FNO(rowid) fileNo,
id,name
from tt1;
BLOCKNUM FILENO ID NAME
---------- ---------- ---------- ------------------------------
135 7 1 AAAA
135 7 2 BBBB
5.使用bbed:
$ bbed parfile=bbed.par
Password: ==>blockedit is default password of bbed
BBED: Release 2.0.0.0.0 - Limited Production on Tue Mar 31 20:39:29 2015
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
************* !!! For Oracle Internal Use only !!! ***************
BBED> set filename '/disk2/oradata/sydb/tbs03.dbf' block 135
FILENAME /disk2/oradata/sydb/tbs03.dbf
BLOCK# 135
BBED> map
File: /disk2/oradata/sydb/tbs03.dbf (0)
Block: 135 Dba:0x00000000
------------------------------------------------------------
KTB Data Block (Table/Cluster)
struct kcbh, 20 bytes @0 =>数据块头
struct ktbbh, 72 bytes @20 =>事物层
struct kdbh, 14 bytes @100 =>数据层
struct kdbt[], 4 bytes @114 ==>表目录层
sb2 kdbr[] @118 ==>行目录层
ub1 freespace[] @122 ==>空闲空间
ub1 rowdata[] @8166 ==>实际行数据
ub4 tailchk @8188 ==>校验码
使用print打印数据块结构信息PRINT[/x|d|u|o|c] [ DBA | FILE | FILENAME | BLOCK | OFFSET | symbol | *symbol ]
BBED> print kcbh
struct kcbh, 20 bytes @0
ub1 type_kcbh @0 0x06 ==>块类型(参考下图:Block Type)
ub1 frmt_kcbh @1 0xa2 ==>块格式
ub1 spare1_kcbh @2 0x00 ==>保留空间
ub1 spare2_kcbh @3 0x00 ==>保留空间
ub4 rdba_kcbh @4 0x01c00087 ==>块地址
ub4 bas_kcbh @8 0x002fa91a ==>base SCN
ub2 wrp_kcbh @12 0x0000 ==>wrap SCN
ub1 seq_kcbh @14 0x01 ==>SCN 序列
ub1 flg_kcbh @15 0x06 (KCBHFDLC, KCBHFCKV) ==> 块属性(0x01 新块,0x02我的理解是延迟修改的块,0x04检查保存的块,0x08 Temporary block)
ub2 chkval_kcbh @16 0xe534 ==>校验码,它的值取决于参数(db_block_checksum)的设置值
ub2 spare3_kcbh @18 0x0000 ==>保留空间
-
BlockTypeNumber
BlockType
01
Undo segment header
02
Undo data block
03
Save undo header
04
Save undo data block
05
Data segment header
06
Trans data,KTB manager data block (with ITL)
07
Temp table data block (no ITL)
08
Sort key
09
Sort run
10
Segment free list block
11
Data file header
(图:Block Type)
打印具体结构值:
BBED> print type_kcbh
ub1 type_kcbh @0 0x06
BBED> print frmt_kcbh
ub1 frmt_kcbh @1 0xa2
事务层:
BBED> print ktbbh
struct ktbbh, 72 bytes @20
ub1 ktbbhtyp @20 0x01 (KDDBTDATA) ==>块类型,01 Data,02 Index
union ktbbhsid, 4 bytes @24 ==>对象号(DBA_OBJECTS.OBJECT_ID)/段号
ub4 ktbbhsg1 @24 0x0001a2c4 ==>对象段号
ub4 ktbbhod1 @24 0x0001a2c4 ==>对象号
struct ktbbhcsc, 8 bytes @28
ub4 kscnbas @28 0x002fbaab ==>SCN Base
ub2 kscnwrp @32 0x0000 ==>SCN Wrap
sb2 ktbbhict @36 2 ==>事务槽号(ITL number)
ub1 ktbbhflg @38 0x32 (NONE) ==>on the free list
ub1 ktbbhfsl @39 0x00 ==>ITL TX free list slot
ub4 ktbbhfnx @40 0x01c00080 ==>下一个空闲块的地址 (next free block dba)
struct ktbbhitl[], 24 bytes @44 ==>事务槽1
struct ktbitxid, 8 bytes @44 ==>xid V$TRANSACTION.XID
ub2 kxidusn @44 0x0005 ==>usn V$TRANSACTION.XIDUSN
ub2 kxidslt @46 0x001f ==>slot V$TRANSACTION.XIDSLOT
ub4 kxidsqn @48 0x000009cb ==>sqn V$TRANSACTION.UBASQN
struct ktbituba, 8 bytes @52 ==>uba
ub4 kubadba @52 0x00c002d1 ==>dba
ub2 kubaseq @56 0x0375 ==>seq
ub1 kubarec @58 0x11 ==>V$TRANSACTION.UBAREC
ub2 ktbitflg @60 0xa000 (KTBFUPB, KTBFCOM)
union _ktbitun, 2 bytes @62
sb2 _ktbitfsc @62 0
ub2 _ktbitwrp @62 0x0000
ub4 ktbitbas @64 0x002fb364
struct ktbbhitl[], 24 bytes @68 ==>事务槽2
struct ktbitxid, 8 bytes @68
ub2 kxidusn @68 0x0000
ub2 kxidslt @70 0x0000
ub4 kxidsqn @72 0x00000000
struct ktbituba, 8 bytes @76
ub4 kubadba @76 0x00000000
ub2 kubaseq @80 0x0000
ub1 kubarec @82 0x00
ub2 ktbitflg @84 0x0000 (NONE)
union _ktbitun, 2 bytes @86
sb2 _ktbitfsc @86 0
ub2 _ktbitwrp @86 0x0000
ub4 ktbitbas @88 0x00000000
数据层:
BBED> print kdbh
struct kdbh, 14 bytes @100
ub1 kdbhflag @100 0x00 (NONE) ==>标记(N=ptcfree hit(clusters),F=do not put on free list,K=flushable cluster keys)
sb1 kdbhntab @101 1 ==>表个数
sb2 kdbhnrow @102 2 ==>块包含的行数
sb2 kdbhfrre @104 -1 ==>是否在空闲列表 -1不在空闲列表
sb2 kdbhfsbo @106 22 ==>空闲空间的开始补偿
sb2 kdbhfseo @108 8066 ==>空闲空间的结束补偿
sb2 kdbhavsp @110 8044 ==>块的平均空间
sb2 kdbhtosp @112 8044 ==>块可以使用的总空间
校验码:
BBED> print tailchk
ub4 tailchk @8188 0xbaab0601 --尾部校验码
tailchk=(低位2个字节)bas_kcbh(0x002fbaab)+(1位字节)type_kcbh(0x06)+(1位字节)seq_kcbh(0x01) ==>值在块头记录)
查找:
数据表存储的值:
SQL>column name format a8
SQL>column dump format a40
SQL>select name,dump(name,16)dump from tt1;
NAME DUMP
-------- ----------------------------------------
AAAA Typ=1 Len=4: 41,41,41,41
BBBB Typ=1 Len=4: 42,42,42,42
FIND[/x|d|u|o|c] numeric/character string [ TOP | CURR ]
|
Find Switch |
DataType |
|
x |
Haxadecimal |
|
d |
Decimal |
|
u |
Unsigned decimal |
|
o |
Octal |
|
c |
Character |
/c 表示通过字符查找:
BBED> find /c AAAA
File: /disk2/oradata/sydb/tbs03.dbf (0)
Block: 135 Offsets: 8184 to 8191 Dba:0x00000000
------------------------------------------------------------------------
41414141 01061aa9
datafile为7,block 135,offset 为8184就是存储AAAA的位置
BBED> dump /v dba 7,135 offset 8184
File: /disk2/oradata/sydb/tbs03.dbf (7)
Block: 135 Offsets: 8184 to 8191 Dba:0x01c00087
-------------------------------------------------------
41414141 0106abba l AAAA..
/x 表示使用十六进制查找:
BBED> find /x 41414141
File: /disk2/oradata/sydb/tbs03.dbf (0)
Block: 135 Offsets: 8184 to 8191 Dba:0x00000000
------------------------------------------------------------------------
41414141 01061aa9
修改值(mode 必须为edit):
MODIFY[/x|d|u|o|c] numeric/character string
通过已知的文件号7,block 135,offset把AAAA的值修改为ABCE
BBED> modify /c ABCE file 7 block 135 offset 8184
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) Y
File: /disk2/oradata/sydb/tbs03.dbf (7)
Block: 135 Offsets: 8184 to 8191 Dba:0x01c00087
------------------------------------------------------------------------
41424345 0106abba
提交修改:
SUM [ DBA | FILE | FILENAME | BLOCK ] [ APPLY ]
BBED> sum apply
Check value for File 7, Block 135:
current = 0xbe37, required = 0xbe37
验证数据块:
VERIFY [ DBA | FILE | FILENAME | BLOCK ]
BBED> verify
DBVERIFY - Verification starting
FILE = /disk2/oradata/sydb/tbs03.dbf
BLOCK = 135
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
验证数据的修改,注:应该在数据库关闭时使用bbed修改数据块,因为当数据库运行时,数据块可能被修改覆盖,这里只是做为测试,并没有其它任何dml或其它操作,当bbed修改数据块并物理保存后,在内存中的数据块并没有刷新,所以此时查询到的数据依然是旧数据:
SQL> column dump format a60
SQL> select name,dump(name,16)dump from tt1;
NAME DUMP
------------------------------ ------------------------------------------------------------
AAAA Typ=1 Len=4: 41,41,41,41
BBBB Typ=1 Len=4: 42,42,42,42
清理buffer_cache和share_pool 触发物理读,数据正确:
SQL>alter system flush buffer_cache;
System altered.
Elapsed: 00:00:00.93
SQL>alter system flush shared_pool;
System altered.
SQL> select name,dump(name,16)dump from tt1;
NAME DUMP
------------------------------ ------------------------------------------------------------
ABCE Typ=1 Len=4: 41,42,43,45
BBBB Typ=1 Len=4: 42,42,42,42
撤销操作:
REVERT [ DBA | FILE | FILENAME | BLOCK ]
撤销当前会话所有操作:
BBED> revert
All changes made in this session will be rolled back. Proceed? (Y/N) y
Reverted file '/disk2/oradata/sydb/tbs03.dbf', block 135
Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y
选择文件和数据块撤销:
BBED> revert dba 7,135
撤销当前会话上一个操作:
UNDO
当前值:
SQL> select name,dump(name,16)dump from tt1;
NAME DUMP
------------------------------ ----------------------------------------
DFCA Typ=1 Len=4: 44,46,43,41
BBBB Typ=1 Len=4: 42,42,42,42
BBED> modify /c ibmc dba 7,135 offset 8184
File: /disk2/oradata/sydb/tbs03.dbf (7)
Block: 135 Offsets: 8184 to 8191 Dba:0x01c00087
------------------------------------------------------------------------
69626d63 0106abba
BBED> sum apply
Check value for File 7, Block 135:
current = 0xa93a, required = 0xa93a
确认值:
SQL> alter system flush shared_pool;
SQL> alter system flush buffer_cache;
SQL> select name,dump(name,16)dump from tt1;
NAME DUMP
------------------------------ ----------------------------------------
ibmc Typ=1 Len=4: 69,62,6d,63
BBBB Typ=1 Len=4: 42,42,42,42
UNDO操作:
BBED> undo
BBED> modify /x 44464341 filename '/disk2/oradata/sydb/tbs03.dbf' block 135. offset 8184.
File: /disk2/oradata/sydb/tbs03.dbf (0)
Block: 135 Offsets: 8184 to 8191 Dba:0x00000000
------------------------------------------------------------------------
44464341 0106abba
<32 bytes per line>
BBED> sum apply
Check value for File 0, Block 135:
current = 0xaf39, required = 0xaf39
--The end
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