Oracle bbed Recovery and retrieve delete data

Recover deleted data

First, create the simulation environment

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Sql> CREATE TABLE Hr.xifenfei (ID number,name varchar2) tablespace xff; Table created. sql> INSERT INTO Hr.xifenfei values (1, ' Xifenfei '); 1 row created. sql> INSERT INTO Hr.xifenfei values (2, ' xff '); 1 row created. Sql> commit; Commit complete. Sql> select * from Hr.xifenfei; ID NAME ———- ——————– 1 Xifenfei 2 Xff Sql> Select rowID, 2 Dbms_rowid.rowid_relative_fno (ROWID) Rel_fno, 3 Dbms_rowid.rowid_block_number (ROWID) Blockno, 4 Dbms_rowid.rowid_row_number (ROWID) rowno 5 from Hr.xifenfei; ROWID rel_fno Blockno Rowno —————— ———- ———- ———- AAAHY3AACAAAAISAAA 2 530 0 Aaahy3aacaaaaisaab 2 530 1 Query File#,block, back restore to use Sql> Delete from Hr.xifenfei where id=2; 1 row deleted. Sql> commit; Commit complete. Sql> select * from Hr.xifenfei; ID NAME ———- ——————– 1 Xifenfei sql> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down.

Second, bbed restore delete data

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[Oracle@localhost ~]$ bbed parfile=/tmp/parfile.cnf Password: Bbed:release 2.0.0.0.0–limited Production on Mon Aug 22 01:52:52 2011 Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved. ************* !!! For Oracle Internal with only!!! *************** Bbed> Show All file# 2 block# 1 OFFSET 0 DBA 0x00800001 (8388609 2,1) Filename/opt/oracle/oradata/xifenfei/xff01.dbf Bifile BIFILE.BBD Listfile/tmp/list BLOCKSIZE 8192 MODE Edit EDIT Unrecoverable IBase Dec Obase Dec WIDTH 80 COUNT 512 LOGFILE LOG.BBD SPOOL No Bbed> Set DBA 2,530 DBA 0x00800212 (8389138 2,530) Bbed> find/c Xff File:/opt/oracle/oradata/xifenfei/xff01.dbf (2) block:530 offsets:8170 to 8191 dba:0x00800212 ———————————————————————— 7866662c 000202c1 02087869 66656e66 65690106 80e2 <32 bytes per line> Bbed> dump/v File:/opt/oracle/oradata/xifenfei/xff01.dbf (2) block:530 offsets:8170 to 8191 dba:0x00800212 ——————————————————- 7866662c 000202c1 02087869 66656e66 l xff,...... xifenf 65690106 80e2 l ei .... <16 bytes per line> bbed> dump/v Offset 8160 File:/opt/oracle/oradata/xifenfei/xff01.dbf (2) block:530 offsets:8160 to 8191 dba:0x00800212 ——————————————————- 0000003c 020202c1 03037866 662c0002 L. <......xff,.. 02c10208 78696665 6e666569 010680e2 l .... Xifenfei ..... <16 bytes per line> bbed> dump/v Offset 8164 File:/opt/oracle/oradata/xifenfei/xff01.dbf (2) block:530 offsets:8164 to 8191 dba:0x00800212 ——————————————————- 020202C1 03037866 662c0002 02c10208 L. Xff,...... 78696665 6e666569 010680e2 l Xifenfei .... <16 bytes per line> bbed> dump/v Offset 8162 File:/opt/oracle/oradata/xifenfei/xff01.dbf (2) block:530 offsets:8162 to 8191 dba:0x00800212 ——————————————————- 003c0202 02c10303 7866662c 000202c1 L. <......xff,.... 02087869 66656e66 65690106 80e2 L.. Xifenfei ..... <16 bytes per line> bbed> dump/v Offset 8163 File:/opt/oracle/oradata/xifenfei/xff01.dbf (2) block:530 offsets:8163 to 8191 dba:0x00800212 ——————————————————- 3c020202 c1030378 66662c00 0202c102 l <......xff,..... 08786966 656e6665 69010680 E2 L. Xifenfei ..... <16 bytes per line> By trying to infer that the offset of 3c Bbed> modify/x 2c Warning:contents of previous bifile would be lost. Proceed? (y/n) Y File:/opt/oracle/oradata/xifenfei/xff01.dbf (2) block:530 offsets:8163 to 8191 dba:0x00800212 ———————————————————————— 2c020202 c1030378 66662c00 0202c102 08786966 656e6665 69010680 E2 <32 bytes per line> Modify 3c to 2c bbed> sum apply Check value for File 2, block 530: Current = 0xb1b9, required = 0xb1b9

Iii. Results of the reconciliation

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Sql> Startup ORACLE instance started. Total System Global area 236000356 bytes Fixed Size 451684 bytes Variable Size 201326592 bytes Database buffers 33554432 bytes Redo buffers 667648 bytes Database mounted. Database opened. Sql> select * from Hr.xifenfei; ID NAME ———- ——————– 1 Xifenfei 2 Xff Description 1 if the data is not deleted: The value of row flag is 32+8+4=44 or 0x2c 2 If the data is deleted: The value of row flag is 32+16+8+4=60 or 0x3c

Retrieve deleted data

Create mock table data

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Sql> CREATE TABLE T_xifenfei (ID number,name varchar2 (10)); Table created. sql> INSERT INTO T_xifenfei values (1, ' Xifenfei '); 1 row created. sql> INSERT INTO T_xifenfei values (2, ' Xifenfei '); 1 row created. Sql> commit; Commit complete. Dump data block Sql> alter system flush Buffer_cache; System altered. Sql> Select Rowid,id,name, 2 Dbms_rowid.rowid_relative_fno (ROWID) Rel_fno, 3 Dbms_rowid.rowid_block_number (ROWID) Blockno, 4 Dbms_rowid.rowid_row_number (ROWID) rowno 5 from Chf.t_xifenfei; ROWID ID NAME rel_fno blockno rowno ------------------ ---------- ---------- ---------- ---------- ---------- AAASDMAAEAAAACVAAA 1 Xifenfei 4 175 0 Aaasdmaaeaaaacvaab 2 Xifenfei 4 175 1 sql> alter system dump DATAFILE 4 block 175; System altered. Dump file contents Block_row_dump: tab 0, row 0, @0x1f89 TL:15 FB:--h-fl--lb:0x1 Cc:2 Col 0: [2] C1 02 Col 1: [8] 6e 66 65 69 tab 0, row 1, @0x1f7a TL:15 FB:--h-fl--lb:0x1 Cc:2 Col 0: [2] C1 03 Col 1: [8] 4e 46 45 49 End_of_block_dump 2012-05-01 05:09:29.287714:kjbmbassert [0XAF.4] End dump data blocks Tsn:4 file#: 4 minblk 175 maxblk 175

Delete table Data

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Sql> Delete from T_xifenfei; 2 rows deleted. Sql> commit; Commit complete. Sql> alter system flush Buffer_cache; System altered. sql> alter system dump DATAFILE 4 block 175; System altered. Dump file contents Block_row_dump: tab 0, row 0, @0x1f89 Tl:2 FB:--hdfl--lb:0x2 tab 0, row 1, @0x1f7a Tl:2 FB:--hdfl--lb:0x2 End_of_block_dump 2012-05-01 05:13:35.214357:kjbmbassert [0XAF.4] End dump data blocks Tsn:4 file#: 4 minblk 175 maxblk 175 By comparing these two dump files, we found 1. Data content is deleted, not really deleted, but to add an identity bit (FD:---D----) 2.fb:--h-fl--(head of row Piece+first data piece+last data piece) It has 8 options for each option value corresponding to bitmask, 32+8+4=44 or 0x2c 3. If a row is removed, row flag is updated and the deleted in bitmask is set to 16. At this point row flag is: 32+16+8+4 = or 0x3c. 4. If we want to retrieve the data to be deleted, we need to change the 3c to 2c.

Close Database

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Sql> select * from Chf.t_xifenfei; No rows selected Sql> select name from V$datafile where file#=4; NAME ------------------------------------------------ /tmp/user01.dbf sql> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. bbed Modify Data bbed> set filename '/tmp/user01.dbf ' Filename/tmp/user01.dbf Bbed> Set block 175 block# 175 Bbed> Set BlockSize 8192 BLOCKSIZE 8192 Bbed> Set Mode Edit MODE Edit Bbed> Map File:/tmp/user01.dbf (0) block:175 dba:0x00000000 ------------------------------------------------------------ KTB Data block (table/cluster) struct KCBH, Bytes @0 struct KTBBH, Bytes @20 struct KDBH, Bytes @100 struct kdbt[1], 4 bytes @114 SB2 Kdbr[2] @118 Ub1 freespace[8036] @122 Ub1 Rowdata[30] @8158 UB4 Tailchk @8188 Bbed> P *kdbr[0] ROWDATA[15] ----------- Ub1 rowdata[15] @8173 0x3c Bbed> P *kdbr[1] ROWDATA[0] ---------- Ub1 Rowdata[0] @8158 0x3c Bbed> m/x 2c Offset 8158 File:/tmp/user01.dbf (0) block:175 offsets:8158 to 8191 dba:0x00000000 ------------------------------------------------------------------------ 2c630202 c1030858 4946454e 46454932 630202c1 02087869 66656e66 65690106 b47e <32 bytes per line> Bbed> m/x 2c offset 8173 File:/tmp/user01.dbf (0) block:175 offsets:8173 to 8191 dba:0x00000000 ------------------------------------------------------------------------ 2c630202 c1020878 6966656e 66656901 06b47e <32 bytes per line> bbed> sum apply Check value for File 0, block 175: Current = 0x4d13, required = 0x4d13

Start Database validation

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sql> Startup ORACLE instance started.   Total System Global area  535662592 bytes Fixed size &nb sp;                1346140 bytes Variable size             411043236 bytes Database buffers          117440512 bytes Redo buffers                 5832704 bytes Database mounted. Database opened. Sql> SELECT * from Chf.t_xifenfei;           ID NAME --------------------           1 Xifenfei          2 Xifenfei