Oracle delete和truncate实践操作之一

实践说明

  本文章主要记录在Oracle中,delete和truncate进行数据删除之后,如何进行数据恢复。由于网上对delete和truncate的区别说明较多,此处不过多介绍两者区别。

  注:由于环境和版本以及其他因素,本文章中并非最佳解决方法,仅供参考。

实践过程

  环境准备

    1、在本机准备Oracle bbed执行程序(需要通过指定包编译获取)  delete主要还原工具

    2、FY_Recover_Data工具下载(HelloDBA大神作品)truncate主要还原工具

  Delete删除恢复过程

    1、准备测试数据

    

 1 SQL> create tablespace test1 datafile '+DATA' size 5M autoextend on next 1M maxsize 15M;
 2 Tablespace created.
 3 
 4 SQL> select TABLESPACE_NAME,FILE_ID,STATUS,FILE_NAME,BYTES/1024/1024 from dba_data_files;
 5 
 6 TABLESPACE_NAME         FILE_ID STATUS    FILE_NAME                                                    BYTES/1024/1024
 7 -------------------- ---------- --------- ------------------------------------------------------------ ---------------
 8 USERS                         4 AVAILABLE +DATA/orcl/users01.dbf                                                  52.5
 9 UNDOTBS1                      3 AVAILABLE +DATA/orcl/undotbs01.dbf                                                 255
10 SYSAUX                        2 AVAILABLE +DATA/orcl/sysaux01.dbf                                                 1060
11 SYSTEM                        1 AVAILABLE +DATA/orcl/system01.dbf                                                  770
12 UNDOTBS2                      5 AVAILABLE +DATA/orcl/undotbs02.dbf                                               82.25
13 TEST1                         6 AVAILABLE +DATA/orcl/datafile/test1.268.1016378251                                   5
14 
15 6 rows selected.
16 
17 SQL> create user test identified by test default tablespace test1;
18 User created.
19 
20 SQL> grant dba to test;
21 Grant succeeded.
22 
23 SQL> conn test/test
24 Connected.
25 SQL> create table t1 as select * from dba_objects where object_id<10;
26 Table created.
27 SQL> commit;
28 
29 Commit complete.

    2、delete操作本质

    在执行delete后,数据并没有在物理上删除,只是把对应记录标记为删除,而且delete后,对表的HWM没有改造,表的大小依然那么大,delete数据后,占用的空间一直都在,别的表记录不能在此写入。

    

 1 SQL> select dbms_rowid.rowid_relative_fno(rowid) file#,dbms_rowid.rowid_block_number(rowid) block#,t.object_id from TEST.T1 t;
 2      FILE#     BLOCK#  OBJECT_ID
 3 ---------- ---------- ----------
 4          6        131          2
 5          6        131          3
 6          6        131          4
 7          6        131          5
 8          6        131          6
 9          6        131          7
10          6        131          8
11          6        131          9
12 
13 8 rows selected.

    上述记录为T1表所在的数据文件6,以及对应的BLOCK#131。通过以下两种方法可以查看其block中对应行的标识。

    方法一、dump出对应的数据块

 1 SQL> alter system dump datafile 6 block 131;
 2 System altered.
 3 
 4 SQL> select spid from v$process where addr=(select paddr from v$session where sid=(select sid from v$mystat where rownum=1)); 
 5 SPID
 6 ------------------------
 7 26716
 8 
 9 
10 [oracle@dbrac1 trace]$ pwd
11 /u01/app/oracle/diag/rdbms/orcl/orcl1/trace
12 [oracle@dbrac1 trace]$ ls -lrt *26716*
13 -rw-r----- 1 oracle asmadmin   614 8月  15 15:34 orcl1_ora_26716.trm
14 -rw-r----- 1 oracle asmadmin 12708 8月  15 15:34 orcl1_ora_26716.trc
15 
16 。。。。。。。。
17 block_row_dump:
18 tab 0, row 0, @0x1f30
19 tl: 80 fb: --H-FL-- lb: 0x0  cc: 14     <==============fb : HFL即代表为正常记录
20 col  0: [ 3]  53 59 53
21 col  1: [ 6]  43 5f 4f 42 4a 23
22 col  2: *NULL*
23 col  3: [ 2]  c1 03
24 col  4: [ 2]  c1 03
25 col  5: [ 7]  43 4c 55 53 54 45 52
26 col  6: [ 7]  78 71 08 18 0c 26 24
27 col  7: [ 7]  78 71 08 18 0c 26 24
28 col  8: [19]  32 30 31 33 2d 30 38 2d 32 34 3a 31 31 3a 33 37 3a 33 35
29 col  9: [ 5]  56 41 4c 49 44
30 col 10: [ 1]  4e
31 col 11: [ 1]  4e
32 col 12: [ 1]  4e
33 col 13: [ 2]  c1 06
34 tab 0, row 1, @0x1ee2
35 tl: 78 fb: --H-FL-- lb: 0x0  cc: 14      <==============fb: HFL即代表为正常记录  HDFL代表删除记录
36 col  0: [ 3]  53 59 53
37 col  1: [ 6]  49 5f 4f 42 4a 23
38 col  2: *NULL*
39 col  3: [ 2]  c1 04
40 col  4: [ 2]  c1 04

    方法二、通过bbed查看相应块行记录

 1 ASMCMD> cp TEST1.268.1016378251 /home/grid/test1.dbf                <===============bbed不能直接读取ASM中数据文件,需要CP出来
 2 copying +DATA/ORCL/DATAFILE/TEST1.268.1016378251 -> /home/grid/test1.dbf
 3 
 4 BBED> info all
 5  File#  Name                                                        Size(blks)
 6  -----  ----                                                        ----------
 7      1  /home/oracle/bbed/asm_disk_header                                    0
 8      2  /home/oracle/bbed/asm_disk_header2                                   0
 9      6  /home/oracle/bbed/test1.dbf                                       1920
10 
11 BBED> set dba 6,131                                                <================设置数据文件6,Block 131
12         DBA             0x01800083 (25165955 6,131)
13 BBED> p *kdbr[0]
14 rowdata[560]
15 ------------
16 ub1 rowdata[560]                            @8108     0x2c        <=================此处2c代表正常记录  3c代表删除记录
17 
18 BBED> x /rcccccccc
19 rowdata[560]                                @8108    
20 ------------
21 flag@8108: 0x2c (KDRHFL, KDRHFF, KDRHFH)
22 lock@8109: 0x00
23 cols@8110:   14
24 
25 col    0[3] @8111: SYS
26 col    1[6] @8115: C_OBJ#
27 col    2[0] @8122: *NULL*
28 col    3[2] @8123: col    4[2] @8126: col    5[7] @8129: CLUSTER
29 col    6[7] @8137: xq...&$
30 col    7[7] @8145: xq...&$
31 col   8[19] @8153: 2013-08-24:11:37:35
32 col    9[5] @8173: VALID
33 col   10[1] @8179: N
34 col   11[1] @8181: N
35 col   12[1] @8183: N
36 col   13[2] @8185: 

    注:以上关于Block的内容可参考 来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/26715884/viewspace-2114424/

    3、删除记录

 1 SQL> delete from test.t1; 
 2 8 rows deleted.
 3 
 4 SQL> commit;
 5 Commit complete.
 6 
 7 SQL> alter system flush buffer_cache;                   <============需要将脏块刷进数据文件
 8 System altered.
 9 
10 
11 SQL> alter system dump datafile 6 block 131;
12 System altered.
13 
14 SQL>  select spid from v$process where addr=(select paddr from v$session where sid=(select sid from v$mystat where rownum=1)); 
15 SPID
16 ------------------------
17 19634
18 
19 [oracle@dbrac1 trace]$ pwd
20 /u01/app/oracle/diag/rdbms/orcl/orcl1/trace
21 [oracle@dbrac1 trace]$ ls -lrt *19634*
22 -rw-r----- 1 oracle asmadmin  322 8月  15 15:50 orcl1_ora_19634.trm
23 -rw-r----- 1 oracle asmadmin 8370 8月  15 15:50 orcl1_ora_19634.trc
24 [oracle@dbrac1 trace]$ vi orcl1_ora_19634.trc
25 。。。。。
26 block_row_dump:
27 tab 0, row 0, @0x1f30
28 tl: 2 fb: --HDFL-- lb: 0x2                           <=================== fb:标识已经变成HDFL,为已删除状态。
29 tab 0, row 1, @0x1ee2
30 tl: 2 fb: --HDFL-- lb: 0x2
31 tab 0, row 2, @0x1e96
32 tl: 2 fb: --HDFL-- lb: 0x2
33 tab 0, row 3, @0x1e4a
34 tl: 2 fb: --HDFL-- lb: 0x2
35 tab 0, row 4, @0x1dfb
36 tl: 2 fb: --HDFL-- lb: 0x2

     4、通过bbed还原数据

 1 ASMCMD> cp TEST1.268.1016378251 /home/grid/test2.dbf
 2 copying +DATA/ORCL/DATAFILE/TEST1.268.1016378251 -> /home/grid/test2.dbf         <=======为了减少麻烦,将数据库关闭后,将文件重新拿出来,命名test2.dbf
 3 BBED> info all
 4  File#  Name                                                        Size(blks)
 5  -----  ----                                                        ----------
 6      1  /home/oracle/bbed/asm_disk_header                                    0
 7      2  /home/oracle/bbed/asm_disk_header2                                   0
 8      6  /home/oracle/bbed/test1.dbf                                       1920
 9      7  /home/oracle/bbed/test2.dbf                                       1920     <========删除数据后的数据文件
10 
11 BBED> set dba 7,131
12         DBA             0x01c00083 (29360259 7,131)
13 BBED> p *kdbr[0]
14 rowdata[560]
15 ------------
16 ub1 rowdata[560]                            @8108     0x3c                          <======标记已调整为3c证明数据处于删除状态
17 BBED> dump
18  File: /home/oracle/bbed/test2.dbf (7)
19  Block: 131              Offsets: 8108 to 8191           Dba:0x01c00083
20 ------------------------------------------------------------------------
21  3c020e03 53595306 435f4f42 4a23ff02 c10302c1 0307434c 55535445 52077871 
22  08180c26 24077871 08180c26 24133230 31332d30 382d3234 3a31313a 33373a33 
23  35055641 4c494401 4e014e01 4e02c106 010641c7 
24 
25  <32 bytes per line>
26 
27 BBED> m /x 2c                                                                <============通过修改数据块标识,调整行记录状态
28  File: /home/oracle/bbed/test2.dbf (7)
29  Block: 131              Offsets: 8108 to 8191           Dba:0x01c00083
30 ------------------------------------------------------------------------
31  2c020e03 53595306 435f4f42 4a23ff02 c10302c1 0307434c 55535445 52077871 
32  08180c26 24077871 08180c26 24133230 31332d30 382d3234 3a31313a 33373a33 
33  35055641 4c494401 4e014e01 4e02c106 010641c7 
34 
35  <32 bytes per line>
36 
37 BBED> sum apply
38 Check value for File 7, Block 131:
39 current = 0x0000, required = 0x0000

BBED> x /rcccccccccc

  rowdata[560] @8108
  ------------
  flag@8108: 0x2c (KDRHFL, KDRHFF, KDRHFH)
  lock@8109: 0x02
  cols@8110: 14

col    0[3] @8111: SYS
col 1[6] @8115: C_OBJ# <===============在还原之后,数据可以查看

    5、验证数据

ASMCMD> rm -rf TEST1.268.1016378251
ASMCMD>  cp /home/grid/test2.dbf +DATA/orcl/DATAFILE/test2.dbf
copying /home/grid/test2.dbf -> +DATA/orcl/DATAFILE/test2.dbf

SQL> startup mount
ORACLE instance started.
Total System Global Area 1043886080 bytes
Fixed Size                  2259840 bytes
Variable Size             645923968 bytes
Database Buffers          390070272 bytes
Redo Buffers                5632000 bytes
Database mounted.
SQL> alter database rename file '+DATA/orcl/DATAFILE/TEST1.268.1016378251' to '+DATA/orcl/DATAFILE/test2.dbf'; 
Database altered.

SQL> alter database open;
Database altered.

SQL>  select OWNER,OBJECT_NAME from test.t1;                         <=============此处查出结果,与第4步结果一致,证明恢复成功
OWNER                          OBJECT_NAME
------------------------------ ----------------------------------------
SYS                            C_OBJ#

    6、总结

    以上过程看似步骤简单,实际上蕴含很多知识点。

    1) Block块删除行后,标识位改变算法(本次实践的重点)

    2)使用bbed读取ASM中数据文件方法

    3)查看Block块内容方法

    4)从本地传文件至ASM磁盘组方法

    5)bbed中一些常用的命令

 

 关于Truncate表的恢复方法,详见下一章节Oracle delete和truncate实践操作之二。 

 

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