ORACLE 如何检查找出损坏索引 ( Corrupt Indexes )

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在Oracle数据库中如何找出损坏索引呢? 下面我们人为构造一个案例,将索引块损坏。如下案例所示:

SQL> create tablespace test_data

 2
datafile
'/u01/app/oracle/oradata/gsp/test_data_01.dbf'

 3
size 200M autoextend off

4
logging

5
segment space management auto

6
extent management local;

 Tablespace created.

 SQL> create tablespace test_index

 2
datafile
'/u01/app/oracle/oradata/gsp/test_idx_01.dbf'

 3
size 200M autoextend off

4
logging

5
segment space management auto

6
extent management local;

 Tablespace created.

SQL> create user kerry

2
identified by 123456

3
default tablespace test_data;

 User created.

 SQL> grant connect to kerry;
SQL> grant resource to kerry;

上述脚本是创建表空间,创建用户kerry并授权,然后使用kerry账号登录数据库,构造测试数据,在TEST表上创建索引IX_TEST

SQL> show user;
USER is "KERRY"
SQL>
 SQL> CREATE TABLE TEST(ID
NUMBER(10), NAME VARCHAR2(64));

 Table created.

 SQL> DECLARE I
NUMBER;

2
BEGIN

3

FOR I IN 1..1000 LOOP

4
INSERT INTO TEST VALUES(I, LPAD('T', 60));
5

 END LOOP;

6
COMMIT;

7
END;

8
/

 PL/SQL procedure successfully completed.

SQL> CREATE INDEX IX_TEST ON KERRY.TEST(NAME) TABLESPACE TEST_INDEX;

 Index created.

然后使用下面脚本找到索引段数据库文件ID,以及索引段的第一个块的块号。

SQL> show user;
USER is "SYS"
SQL> col segment_name for a32;



 SQL> col header_file for 9999;



 SQL> col header_block for 9999;



SQL> select segment_name



 2
 ,header_file




3
 ,header_block



 4
 ,blocks




 5
from dba_segments ds



6
where ds.owner='KERRY' and ds.segment_name='IX_TEST';

SEGMENT_NAME

 HEADER_FILE HEADER_BLOCK

 BLOCKS
-------------------------------- ----------- ------------ ----------
IX_TEST



8
130
16

 SQL>

构造坏块的方法有不少(例如BBED等),这里我们使用RMAN下面的命令clear,可以标记数据块为corrupt,标记数据文件8中130号数据块为坏块。

[oracle@DB-Server ~]$ rman target /

 Recovery Manager: Release 11.2.0.1.0 - Production on Thu Sep 13 17:41:05 2018

 Copyright (c) 1982, 2009, Oracle and/or its affiliates.
All rights reserved.

 connected to target database: GSP (DBID=644393201)

 RMAN> recover datafile 8 block 130 clear;

 Starting recover at 13-SEP-18
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=12 device type=DISK
Finished recover at 13-SEP-18

 RMAN>

那么我们先来看看使用那些方法验证索引损坏了,测试验证一下看看是否可行。 

1:使用ANALYZE分析验证索引结构

[oracle@DB-Server ~]$ sqlplus / as sysdba

 SQL*Plus: Release 11.2.0.1.0 Production on Thu Sep 13 17:42:03 2018

 Copyright (c) 1982, 2009, Oracle.
All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

 SQL> analyze index kerry.ix_test validate structure;
analyze index kerry.ix_test validate structure
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 8, block # 130)
ORA-01110: data file 8: '/u01/app/oracle/oradata/gsp/test_idx_01.dbf'

如上截图所示,如果索引损坏(Corrupt Index),那么使用analyze index validate structure就会报错。要检查整个数据库所有的损坏索引(Corrupt Indexes)的话,就可以借助下面脚本: 

spool analy_index.sql
SET PAGESIZE 50000;
SELECT

 'ANALYZE INDEX
' || OWNER || '.' || INDEX_NAME|| ' VALIDATE STRUCTURE;' FROM DBA_INDEXES;

 spool off;

 @analy_index.sql

2:使用系统视图v$database_block_corruption查看损坏索引

如下所示,我们使用这个脚本来查看出现坏块的索引,发现这个脚本无法找出坏块索引。

set pagesize 50 linesize 170
col segment_name format a30
col partition_name format a30
SELECT DISTINCT file#,
segment_name,
segment_type,
tablespace_name,
partition_name
 FROM
 dba_extents a,
v$database_block_corruption b
 WHERE
a.file_id = b.file#
AND a.block_id <= b.block#
AND a.block_id + a.blocks >= b.block#;

原因分析如下,视图v$database_block_corruption中有坏块记录,但是我们将索引段的第一个块标记为坏块后,在dba_extents中没有该索引段的记录了。所以这种情况下的索引损坏,这个SQL语句根本无法找出坏块索引。

SQL> SELECT file_id,

 2
segment_name,

 3
segment_type

 4
FROM
 dba_extents

 5
WHERE
file_id = 8 ;

 no rows selected

 SQL> SELECT file_id,

 2
segment_name,

 3
segment_type

 4 FROM
 dba_extents

 5
WHERE
owner = 'KERRY';

FILE_ID SEGMENT_NAME

 SEGMENT_TYPE
---------- -------------------------------- ------------------
 7 TEST


TABLE
 7 TEST


TABLE

 SQL>

因为一个段的第一个区的第一个块是FIRST LEVEL BITMAP BLOCK,第二个块是SECOND LEVEL BITMAP BLOCK,这两个块是用来管理free block的,第三个块是PAGETABLE SEGMENT HEADER,这个块才是segment里的HEADER_BLOCK,再后面的块就是用来记录数据的。关于这些知识,可以参考我博客ORACLE关于段的HEADER_BLOCK的一点浅析。我们最上面的例子,是将第一个块构造为坏块,所以导致上面SQL无法查出。 我们重新构造案例,如我们将索引段的数据块构造为坏块,例如下面,将块号148人为构造坏块。那么此时这个脚本就能找出坏块索引了。所以综上述实验可以看出,这个脚本查找坏块索引是有条件的,要看索引段损坏的块是什么类型

SQL> SELECT FILE_ID,

 2
BLOCK_ID,

 3
BLOCKS
 FROM
 DBA_EXTENTS

 4

5
WHERE
OWNER ='&OWNER'

6
 AND SEGMENT_NAME = '&TABLE_NAME';
 Enter value for owner: KERRY
old
 5: WHERE
OWNER ='&OWNER'
new
 5: WHERE
OWNER ='KERRY'
Enter value for table_name: IX_TEST
old
 6:
AND SEGMENT_NAME = '&TABLE_NAME'
new
 6:
AND SEGMENT_NAME = 'IX_TEST'

FILE_ID
 BLOCK_ID

 BLOCKS
---------- ---------- ----------
 8

144
8
 8

152
8

 SQL> SELECT HEADER_FILE

2
 , HEADER_BLOCK

3
 , BYTES

4
 , BLOCKS

5
 , EXTENTS
 FROM DBA_SEGMENTS

 6

7
WHERE OWNER='&OWNER' AND SEGMENT_NAME='&SEGMENT_NAME';
Enter value for owner: KERRY
Enter value for segment_name: IX_TEST
old
 7: WHERE OWNER='&OWNER' AND SEGMENT_NAME='&SEGMENT_NAME'
new
 7: WHERE OWNER='KERRY' AND SEGMENT_NAME='IX_TEST'

 HEADER_FILE HEADER_BLOCK
BYTES

 BLOCKS

EXTENTS
----------- ------------ ---------- ---------- ----------

8
146

 131072
16
2

 SQL>

RMAN> recover datafile 8 block 148 clear;

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