[20190213]学习bbed-恢复删除的数据.txt

[20190213]学习bbed-恢复删除的数据.txt --//以前也做过类似测试,当时在用bbed做verify时错误都不处理,当时的想法就是能读出就ok了. --//而且当时也做成功,纯粹是依葫芦画瓢,按照别人的blog重复操作,一点不理解为什么这样做. --//重复测试: 1.环境: SCOTT@book> @ ver1 PORT_STRING                    VERSION        BANNER ------------------------------ -------------- -------------------------------------------------------------------------------- x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production SCOTT@book> create table dept1 as select * from dept ; Table created. SCOTT@book> select rowid,dept1.* from dept1; ROWID                  DEPTNO DNAME          LOC ------------------ ---------- -------------- ------------- AAAWPyAAEAAAAILAAA         10 ACCOUNTING     NEW YORK AAAWPyAAEAAAAILAAB         20 RESEARCH       DALLAS AAAWPyAAEAAAAILAAC         30 SALES          CHICAGO AAAWPyAAEAAAAILAAD         40 OPERATIONS     BOSTON SCOTT@book> @ rowid AAAWPyAAEAAAAILAAA     OBJECT       FILE      BLOCK        ROW ROWID_DBA            DBA                  TEXT ---------- ---------- ---------- ---------- -------------------- -------------------- ----------------------------------------      91122          4        523          0  0x100020B           4,523                alter system dump datafile 4 block 523 ; SCOTT@book> delete from dept1 where deptno=10; 1 row deleted. SCOTT@book> commit ; Commit complete. SCOTT@book> alter system checkpoint ; System altered. 2.使用bbed恢复测试: BBED> set dba 4,523         DBA             0x0100020b (16777739 4,523) BBED> x /rncc  *kdbr[1] rowdata[44]                                 @8140 ----------- flag@8140: 0x2c (KDRHFL, KDRHFF, KDRHFH) lock@8141: 0x00 cols@8142:    3 col    0[2] @8143: 20 col    1[8] @8146: RESEARCH col    2[6] @8155: DALLAS BBED> x /rncc  *kdbr[0] rowdata[66]                                 @8162 ----------- flag@8162: 0x3c (KDRHFL, KDRHFF, KDRHFD, KDRHFH) lock@8163: 0x02 cols@8164:    0 --//可以看出删除的flag=0x3c(正常没有发生行链接或者迁移的情况下). BBED> assign offset 8162=0x2c; Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y ub1 rowdata[0]                              @8162     0x2c BBED> x /rncc  *kdbr[0] rowdata[66]                                 @8162 ----------- flag@8162: 0x2c (KDRHFL, KDRHFF, KDRHFH) lock@8163: 0x02 cols@8164:    3 col    0[2] @8165: 10 col   1[10] @8168: ACCOUNTING col    2[8] @8179: NEW YORK --//OK,现在已经正常读出. BBED> sum apply Check value for File 4, Block 523: current = 0x8dc2, required = 0x8dc2 BBED> verify DBVERIFY - Verification starting FILE = /mnt/ramdisk/book/users01.dbf BLOCK = 523 Block Checking: DBA = 16777739, Block Type = KTB-managed data block data header at 0x7f9b8221527c kdbchk: the amount of space used is not equal to block size         used=118 fsc=24 avsp=7946 dtl=8064 Block 523 failed with check code 6110 --//以前verify出错,我基本不做修复,因为这些数值不是很好理解. --//实际上计算公司是  --//dtl-used-fsc=avsp 或者 used+fsc+avsp=dtl. --//8064-118-24 = 7922 --//前面显示(lock@8163: 0x02)事务使用ITL槽是1(从0开始记数). BBED> p ktbbh.ktbbhitl[1] struct ktbbhitl[1], 24 bytes                @68    struct ktbitxid, 8 bytes                 @68       ub2 kxidusn                           @68       0x000a       ub2 kxidslt                           @70       0x0007       ub4 kxidsqn                           @72       0x000058bf    struct ktbituba, 8 bytes                 @76       ub4 kubadba                           @76       0x00c001e4       ub2 kubaseq                           @80       0x11ad       ub1 kubarec                           @82       0x1d    ub2 ktbitflg                             @84       0x2001 (KTBFUPB)    union _ktbitun, 2 bytes                  @86       sb2 _ktbitfsc                         @86       24       ub2 _ktbitwrp                         @86       0x0018    ub4 ktbitbas                             @88       0x1775b85d --//_ktbitfsc,_ktbitwrp类似C语言的union,当设置提交标识时,表示scn_wrap.其它表示dml操作回收的空间(不包括flag,lock标识). --//如果insert或者update需要空间比原来大,记录是0. BBED> x /rncc  *kdbr[0] rowdata[66]                                 @8162 ----------- flag@8162: 0x2c (KDRHFL, KDRHFF, KDRHFH) lock@8163: 0x02 cols@8164:    3 col    0[2] @8165: 10 col   1[10] @8168: ACCOUNTING col    2[8] @8179: NEW YORK --//1+1+2+1+10+1+8 = 24,正好等于回收空间.注意每个字段前有1个长度指示器(如果字符串长度大于250,需要3个字节) BBED> assign ktbbh.ktbbhitl[1]._ktbitun._ktbitfsc=0; sb2 _ktbitfsc                               @86       0 BBED> sum apply Check value for File 4, Block 523: current = 0x8dda, required = 0x8dda BBED> verify DBVERIFY - Verification starting FILE = /mnt/ramdisk/book/users01.dbf BLOCK = 523 Block Checking: DBA = 16777739, Block Type = KTB-managed data block data header at 0x1a98e7c kdbchk: space available on commit is incorrect         tosp=7972 fsc=0 stb=0 avsp=7946 Block 523 failed with check code 6111 --//计算公式是tosp=fsc+stb+avsp,stb 标识什么不理解. BBED> p kdbh struct kdbh, 14 bytes                       @124    ub1 kdbhflag                             @124      0x00 (NONE)    sb1 kdbhntab                             @125      1    sb2 kdbhnrow                             @126      4    sb2 kdbhfrre                             @128     -1    sb2 kdbhfsbo                             @130      26    sb2 kdbhfseo                             @132      7972    sb2 kdbhavsp                             @134      7946    sb2 kdbhtosp                             @136      7972 BBED> assign kdbhtosp=kdbhavsp; sb2 kdbhtosp                                @136      7946 BBED> assign kdbh.kdbhtosp=kdbh.kdbhavsp; sb2 kdbhtosp                                @136      7946 --//两者写法都支持. BBED> sum apply Check value for File 4, Block 523: current = 0x8df4, required = 0x8df4 BBED> verify DBVERIFY - Verification starting FILE = /mnt/ramdisk/book/users01.dbf BLOCK = 523 --//OK. SCOTT@book> alter system flush buffer_cache; System altered. SCOTT@book> select rowid,dept1.* from dept1; ROWID                  DEPTNO DNAME          LOC ------------------ ---------- -------------- ------------- AAAWPyAAEAAAAILAAA         10 ACCOUNTING     NEW YORK AAAWPyAAEAAAAILAAB         20 RESEARCH       DALLAS AAAWPyAAEAAAAILAAC         30 SALES          CHICAGO AAAWPyAAEAAAAILAAD         40 OPERATIONS     BOSTON --//随便说一下,不要再使用modify修改信息,这样非常容易出错(要考虑大小头问题).使用assign简单快捷,很少出错. --//简直就像小时候玩变形金刚的游戏.