利用构造ROWID脚本实现无备份情况下绕过ORA-1578、8103、1410、00600 kdsgrp1 等坏块场景

利用构造rowid的方式来实现绕过坏块恢复正常的表数据库，也可以通过该脚本尝试读取坏块内部未损坏的数据，只是脚本需要修改。

SKIP ORA-1578 ORA-8103 ORA-1410

REM Create a new table based on the table that is producing errors with no rows:

create table <new table name>
as
select *
from   <original table name>
where  1=2;

REM Create the table to keep track of ROWIDs pointing to affected rows:

create table bad_rows (row_id rowid, oracle_error_code number);

set serveroutput on

DECLARE
TYPE RowIDTab IS TABLE OF ROWID INDEX BY BINARY_INTEGER;

CURSOR c1 IS select /*+ index_ffs(tab1 <index name>) parallel(tab1) */ rowid
from <original table name> tab1
where <indexed column> is NOT NULL
order by rowid;

r RowIDTab;
rows NATURAL := 20000;
bad_rows number := 0 ;
errors number;
error_code number;
myrowid rowid;
BEGIN
OPEN c1;
LOOP
FETCH c1 BULK COLLECT INTO r LIMIT rows;
EXIT WHEN r.count=0;
BEGIN
FORALL i IN r.FIRST..r.LAST SAVE EXCEPTIONS
insert into <new table name>
select /*+ ROWID(A) */ <list of columns from table (ie col1, col2,..)>
from <original table name> A where rowid = r(i);
EXCEPTION
when OTHERS then
BEGIN
errors := SQL%BULK_EXCEPTIONS.COUNT;
FOR err1 IN 1..errors LOOP
error_code := SQL%BULK_EXCEPTIONS(err1).ERROR_CODE;
if error_code in (1410, 8103, 1578) then
myrowid := r(SQL%BULK_EXCEPTIONS(err1).ERROR_INDEX);
bad_rows := bad_rows + 1;
insert into bad_rows values(myrowid, error_code);
else
raise;
end if;
END LOOP;
END;
END;
commit;
END LOOP;
commit;
CLOSE c1;
dbms_output.put_line('Total Bad Rows: '||bad_rows);
END;
/

Notes:

• Replace the next values in the plsql script by the values of the affected table: <index name>, <original table name>, <indexed column>, <list of columns from table (ie col1, col2,..)>

• <index name> should be replaced by preferrable a Primary Key index.

• If a Primary Key index is used, remove the where condition:  “where <indexed column> is NOT NULL”

• The “order by rowid” clause is to get the rows ordered by blocks so a batch of Inserts finds the block in the buffer cache.  Otherwise, one rowid can bring one block from the table and insert just one row, the next rowid brings a different row and insert one row as opposed of finding the same previous block.

• The idea is to get the rowid’s from an existent index, then get all the columns from the table for each rowid and insert these rows into the new table. Using the “index” hint, allows the optimizer to choose the most appropriated index to scan the table based on the indexed column.

• Make sure that the select in the plsql is using an index. One way to verify if the index is used is to get an execution plan from sqlplus:

explain plan for
select /*+ index_ffs(tab1 <index name>) parallel(tab1) */ rowid
from <original table name> tab1
where <indexed column> is NOT NULL
order by rowid;

set lines 200
@?/rdbms/admin/utlxplp</div>

• Note that the plsql executes an INSERT for 20000 rows and COMMIT. If it is required to change this, adjust the value of rows. e.g.:

• If 'Total Bad Rows:' displays 0 and it is known for certain that there is a block incorrect on disk that is causing the ORA-8103, , then it means that the block is empty (no rows) and there is not data loss.

SKIP ORA-600 in a Table

 

This is useful when the ORA-600 is produced by a non-existent chained row (invalid nrid) like ORA-600 [kdsgrp1] and when event 10231 does not work.

drop table bad_rows;
create table bad_rows (row_id ROWID
,oracle_error_code number);

rem Create the new empty table:

create table &&new_table
as select *
from &&affected_table
where 1=2;


set serveroutput on
declare
n number:=0;
bad_rows number := 0;
error_code number;
ora600 EXCEPTION;
PRAGMA EXCEPTION_INIT(ora600, -600);
begin
for i in (select rowid rid from  &&affected_table)  loop
begin
insert into  &&new_table
select *
from &&affected_table
where rowid=i.rid;
n:=n+1;
exception
when ora600 then
bad_rows := bad_rows + 1;
insert into bad_rows values(i.rid,600);
commit;
when others then
error_code:=SQLCODE;
bad_rows := bad_rows + 1;
insert into bad_rows values(i.rid,error_code);
commit;
end;
end loop;
dbms_output.put_line('Total Bad Rows: '||bad_rows);
dbms_output.put_line('Total Good rows: '||n);
end;
/

SKIP ORA-600 in IOT

This is useful when the ORA-600 is produced by a non-existent chained row (invalid nrid) like ORA-600 [kdsgrp1] and when event 10231 does not work for an Index Organized Table (IOT).

drop table bad_rows;
create table bad_rows (row_id UROWID
,oracle_error_code number);

rem Create the new empty table:

create table &&new_table
as select *
from &&affected_table
where 1=2;


set serveroutput on
declare
n number:=0;
bad_rows number := 0;
error_code number;
ora600 EXCEPTION;
PRAGMA EXCEPTION_INIT(ora600, -600);
begin
for i in (select /*+ INDEX_FFS(IOT_1) */ rowid rid from  &&affected_table IOT_1)  loop
begin
insert into  &&new_table
select *
from &&affected_table
where rowid=i.rid;
n:=n+1;
exception
when ora600 then
bad_rows := bad_rows + 1;
insert into bad_rows values(i.rid,600);
commit;
when others then
error_code:=SQLCODE;
bad_rows := bad_rows + 1;
insert into bad_rows values(i.rid,error_code);
commit;
end;
end loop;
dbms_output.put_line('Total Bad Rows: '||bad_rows);
dbms_output.put_line('Total Good rows: '||n);
end;
/