dbms_repair包修复损坏的数据块

dbms_repair包含修复损坏数据块的存储过程，可以检查表和索引数据块损坏的情况，然后标记坏块，再使用表的时候会绕过坏块，但是坏块中的数据会丢失。

---创建测试表空间

SYS@orcl>create tablespace test datafile '/u01/app/oracle/oradata/orcl/test01.dbf' size 5m;

Tablespace created.

---创建测试表

SYS@orcl>create table scott.test tablespace test as select * from dba_objects where rownum<=3000;

Table created.

SYS@orcl>select count(*) from scott.test;

COUNT(*)

----------

3000

---创建索引

SYS@orcl>create index scott.idx_obj on scott.test(object_name) tablespace users;

Index created.

---查出包含行记录的数据块

SYS@orcl>select distinct dbms_rowid.rowid_block_number(rowid) from scott.test order by 1;

DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)

------------------------------------

131

132

133

134

135

136

137

138

139

140

141

DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)

------------------------------------

142

143

145

146

147

148

149

150

151

152

153

DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)

------------------------------------

154

155

156

157

158

159

161

162

163

164

165

DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID)

------------------------------------

166

167

168

169

170

171

39 rows selected.

---破坏138、156、163数据块的内容，这里的char是建立的一个包含4096个字节的文件

[oracle@ora ~]$ dd if=char of=/u01/app/oracle/oradata/orcl/test01.dbf bs=8192 conv=notrunc seek=138 count=1

0+1 records in

0+1 records out

4096 bytes (4.1 kB) copied, 2.5423e-05 s, 161 MB/s

[oracle@ora ~]$ dd if=char of=/u01/app/oracle/oradata/orcl/test01.dbf bs=8192 conv=notrunc seek=156 count=1

0+1 records in

0+1 records out

4096 bytes (4.1 kB) copied, 1.8299e-05 s, 224 MB/s

[oracle@ora ~]$ dd if=char of=/u01/app/oracle/oradata/orcl/test01.dbf bs=8192 conv=notrunc seek=163 count=1

0+1 records in

0+1 records out

4096 bytes (4.1 kB) copied, 2.3117e-05 s, 177 MB/s

---清除buffer cache的内容

SYS@orcl>alter system flush buffer_cache;

System altered.

SYS@orcl>select * from scott.test;

…………省略…………

OWNER

------------------------------

OBJECT_NAME

--------------------------------------------------------------------------------

SUBOBJECT_NAME OBJECT_ID DATA_OBJECT_ID OBJECT_TYPE

------------------------------ ---------- -------------- -------------------

CREATED LAST_DDL_ TIMESTAMP STATUS T G S NAMESPACE

--------- --------- ------------------- ------- - - - ----------

EDITION_NAME

------------------------------

17-SEP-11 17-SEP-11 2011-09-17:09:46:29 VALID N N N 1

ERROR:

ORA-01578: ORACLE data block corrupted (file # 6, block # 138)

ORA-01110: data file 6: '/u01/app/oracle/oradata/orcl/test01.dbf'

555 rows selected.

---创建Repair 表

SYS@orcl>begin

dbms_repair.admin_tables (

table_name => 'REPAIR_TABLE',

table_type => dbms_repair.repair_table,

action => dbms_repair.create_action,

tablespace => 'USERS');

end;

/

PL/SQL procedure successfully completed.

---创建Orphan Key 表

SYS@orcl>

begin

dbms_repair.admin_tables (

table_name => 'ORPHAN_KEY_TABLE',

table_type => dbms_repair.orphan_table,

action => dbms_repair.create_action,

tablespace => 'USERS');

end;

/

PL/SQL procedure successfully completed.

---检查坏块

SYS@orcl>set serveroutput on

declare

num_corrupt int;

begin

num_corrupt :=0;

dbms_repair.check_object(

schema_name =>'SCOTT',

object_name =>'TEST',

repair_table_name =>'REPAIR_TABLE',

corrupt_count =>num_corrupt);

dbms_output.put_line('number corrupt:' || to_char(num_corrupt));

end;

/

number corrupt:3

PL/SQL procedure successfully completed.

SYS@orcl>select object_name, block_id, corrupt_type, marked_corrupt, repair_description from repair_table;

OBJECT_NAM BLOCK_ID CORRUPT_TYPE MARKED_COR REPAIR_DESCRIPTION

---------- ---------- ------------ ---------- ------------------------------

TEST 138 6148 TRUE mark block software corrupt

TEST 156 6148 TRUE mark block software corrupt

TEST 163 6148 TRUE mark block software corrupt

---定位坏块

SYS@orcl>set serveroutput on

declare

cc number;

begin

dbms_repair.fix_corrupt_blocks(schema_name => 'SCOTT',

object_name => 'TEST',

fix_count => cc);

dbms_output.put_line('Number of blocks fixed: ' || to_char(cc));

end;

/

Number of blocks fixed: 0

PL/SQL procedure successfully completed.

---查询丢失数据的rowid

SYS@orcl>set serveroutput on

declare

cc number;

begin

dbms_repair.dump_orphan_keys

(

schema_name => 'SCOTT',

object_name => 'IDX_OBJ',

object_type => dbms_repair.index_object,

repair_table_name => 'REPAIR_TABLE',

orphan_table_name=> 'ORPHAN_KEY_TABLE',

key_count => cc

);

dbms_output.put_line('Number of orphan keys: ' || to_char(cc));

end;

/

Number of orphan keys: 233

PL/SQL procedure successfully completed.

---跳过坏块

SYS@orcl>begin

dbms_repair.skip_corrupt_blocks(schema_name =>'SCOTT',object_name => 'TEST',flags => 1);

end;

/

PL/SQL procedure successfully completed.

SYS@orcl>select * from scott.test;

…………省略…………

OWNER OBJECT_NAM SUBOBJECT_NAME

------------------------------ ---------- ------------------------------

OBJECT_ID DATA_OBJECT_ID OBJECT_TYPE CREATED LAST_DDL_

---------- -------------- ------------------- --------- ---------

TIMESTAMP STATUS T G S NAMESPACE EDITION_NAME

------------------- ------- - - - ---------- ------------------------------

S_GROUP

3002 VIEW 17-SEP-11 17-SEP-11

2011-09-17:09:47:11 VALID N N N 1

2767 rows selected.

---丢失233条记录，丢失记录的rowid可以在ORPHAN_KEY_TABLE表中找到

---重建索引

SYS@orcl>alter index scott.idx_obj rebuild;

Index altered.

用这种方法可以找回部分数据，也可以找回建了索引的值，但是使用dbv再检查test表空间的数据文件时，仍然会显示有损坏的数据块，这时需要把test表的数据全部导出，再重建表或者表空间，然后再把找回的数据导入数据库，推荐用expdp/impdp命令做，可以彻底消除dbv检查到的坏块。