坏块的处理方法：

坏块的处理方法：
　　ROWID RANGE SCAN
　　首先我们要知道dbms_rowid的使用方法：
sys@orcl>select text from user_source where name='DBMS_ROWID';
　　这里有详细的说明，不用再去翻什么资料了。
　　使用DBMS_ROWID 确定坏块的ROWID RANGE
　　LOW_RID INSIDE the corrupt block:
　　SELECT dbms_rowid.rowid_create(1,<object_id>,<relative_fno>,<block_id>,0) from DUAL;
　　HI_RID AFTER the corrupt block:
　　dbms_rowid.rowid_create(1,<object_id>,<relative_fno>,<block_id>+1,0) from DUAL;
scott@ORCL>create table t as select * from all_objects;
　　建一个临时表
　　CREATE TABLE temp_t AS SELECT * FROM t Where 1=0;
sys@ORCL>select object_id from all_objects where wner='SCOTT' and object_name='T';
　　OBJECT_ID
　　----------
　　53605
sys@ORCL>select RELATIVE_FNO,block_id,blocks from dba_extents where wner='SCOTT' and segment_name='T' order by block_id;
　　RELATIVE_FNO BLOCK_ID BLOCKS
　　------------ ---------- ----------
　　4 625 8
　　4 649 8
　　4 657 8
　　4 697 8
　　4 705 8
　　4 713 8
　　4 721 8
　　4 801 8
　　4 809 8
　　4 817 8
　　4 825 8
　　4 833 8
　　4 841 8
　　4 849 8
　　4 857 8
　　4 865 8
　　4 905 128
　　4 1033 128
　　4 1161 128
　　4 1289 128
　　4 1417 128
sys@ORCL>select dbms_rowid.rowid_create(1,53605,4,628,0) from dual;
　　DBMS_ROWID.ROWID_C
　　------------------
　　AAANFlAAEAAAAJ0AAA
　　确定一个块的hirowid：
sys@orcl>select dbms_rowid.rowid_create(1,53605,4,629,0) from dual;
　　DBMS_ROWID.ROWID_C
　　------------------
　　AAANFlAAEAAAAJ1AAA

到这步我们也可以知道一个块中存放了多少条记录：
scott@ORCL>select count(*) from t where rowid>='AAANFlAAEAAAAJ0AAA' and rowid<'AAANFlAAEAAAAJ1AAA';
　　COUNT(*)
　　----------
　　91
　　保存未损坏的数据
　　declare
　　cursor l_cur
　　is
　　select block_id,blocks from dba_extents
　　where wner='SCOTT' and segment_name='T';
　　i pls_integer;
　　m pls_integer;
　　t pls_integer;
　　low_rowid rowid;
　　high_rowid rowid;
　　begin
　　open l_cur;
　　fetch l_cur into i,m;
　　while(l_cur%found) loop
　　for t in i..i+m loop
　　select dbms_rowid.rowid_create(1,53605,4,t,0) into low_rowid from dual;
　　select dbms_rowid.rowid_create(1,53605,4,t+1,0) into high_rowid from dual;
　　insert into temp_t select /*+rowid(a)*/ * from t a where rowid>=low_rowid and
　　rowid<high_rowid;
　　end loop;
　　fetch l_cur into i,m;
　　end loop;
　　close l_cur;
　　end;
　　如果出现重复行，可以这样删除 之：
　　SQL> delete from temp_t where rowid not in (select min(rowid) from temp_t group by object_id);
　　405 rows deleted.