对于某些极端情况下，segment header出现损坏的对象该如何处理,这里通过一个实验来说明这类情况该如何处理,创建表并查询相关segment信息
SQL> create tablespace t_xff datafile '/u01/app/oracle/oradata/orcl/t_xifenfei01.dbf' size 128M autoextend on;
Tablespace created.
SQL> create table t_xifenfei tablespace t_xff as select * from dba_objects;
Table created.
SQL> select header_file,header_block from dba_SEGMENTS where segment_name='T_XIFENFEI' and owner='SYS';
HEADER_FILE HEADER_BLOCK
----------- ------------
5 130
----segment header 为 file 5，block 130
SQL> select EXTENT_ID , FILE_ID ,BLOCK_ID from dba_extents where segment_name='T_XIFENFEI' and owner='SYS';
EXTENT_ID FILE_ID BLOCK_ID
---------- ---------- ----------
0 5 128
1 5 136
2 5 144
3 5 152
4 5 160
5 5 168
6 5 176
7 5 184
8 5 192
9 5 200
10 5 208
11 5 216
12 5 224
13 5 232
14 5 240
15 5 248
16 5 256
17 5 384
18 5 512
19 5 640
20 5 768
21 5 896
22 5 1024
23 5 1152
24 5 1280
25 rows selected.
---有25个extent信息
SQL> select * from dba_free_space where file_id=5;
TABLESPACE_NAME FILE_ID BLOCK_ID BYTES BLOCKS
------------------------------ ---------- ---------- ---------- ----------
RELATIVE_FNO
------------
T_XFF 5 1408 122683392 14976
5
--空闲block是从1408开始
模拟segment header损坏(通过dd破坏block)
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL>
SQL>
SQL>
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@xifenfei ~]$
[oracle@xifenfei ~]$
[oracle@xifenfei ~]$echo xifenfei.com|dd of=/u01/app/oracle/oradata/orcl/t_xifenfei01.dbf bs=8192 conv=notrunc seek=130
0+1 records in
0+1 records out
17 bytes (17 B) copied, 5.4389e-05 s, 313 kB/s
[oracle@xifenfei ~]$ dbv file=/u01/app/oracle/oradata/orcl/t_xifenfei01.dbf
DBVERIFY: Release 11.2.0.4.0 - Production on Wed Apr 13 20:29:41 2022
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
DBVERIFY - Verification starting : FILE = /u01/app/oracle/oradata/orcl/t_xifenfei01.dbf
Page 130 is marked corrupt
Corrupt block relative dba: 0x01400082 (file 5, block 130)
Bad header found during dbv:
Data in bad block:
type: 119 format: 7 rdba: 0x65666978
last change scn: 0x632e.6965666e seq: 0x6f flg: 0x6d
spare1: 0x77 spare2: 0x2e spare3: 0x0
consistency value in tail: 0xada72301
check value in block header: 0xf30a
computed block checksum: 0x5eb9
DBVERIFY - Verification complete
Total Pages Examined : 16384
Total Pages Processed (Data) : 1234
Total Pages Failing (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing (Index): 0
Total Pages Processed (Other): 154
Total Pages Processed (Seg) : 0
Total Pages Failing (Seg) : 0
Total Pages Empty : 14995
Total Pages Marked Corrupt : 1
Total Pages Influx : 0
Total Pages Encrypted : 0
Highest block SCN : 6466979 (0.6466979)
查询表数据报错
[oracle@xifenfei ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Wed Apr 13 20:29:48 2022
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 734892032 bytes
Fixed Size 2256872 bytes
Variable Size 452984856 bytes
Database Buffers 276824064 bytes
Redo Buffers 2826240 bytes
Database mounted.
Database opened.
SQL> select count(1) from t_xifenfei;
select count(1) from t_xifenfei
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 5, block # 130)
ORA-01110: data file 5: '/u01/app/oracle/oradata/orcl/t_xifenfei01.dbf'
查询extent信息为空
SQL> select EXTENT_ID , FILE_ID ,BLOCK_ID from dba_extents where segment_name='T_XIFENFEI' and owner='SYS';
no rows selected
SQL> select header_file,header_block from dba_SEGMENTS where segment_name='T_XIFENFEI' and owner='SYS';
HEADER_FILE HEADER_BLOCK
----------- ------------
5 130
SQL> select * from dba_free_space where file_id=5;
TABLESPACE_NAME FILE_ID BLOCK_ID BYTES BLOCKS
------------------------------ ---------- ---------- ---------- ----------
RELATIVE_FNO
------------
T_XFF 5 1408 122683392 14976
5
尝试删除表报错
SQL> drop table t_xifenfei;
drop table t_xifenfei
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 5, block # 130)
ORA-01110: data file 5: '/u01/app/oracle/oradata/orcl/t_xifenfei01.dbf'
通过加purge删除成功
SQL> drop table t_xifenfei purge;
Table dropped.
删除表成功，但是磁盘空间未释放，通过查询确认变为一个临时段
SQL> select * from dba_free_space where file_id=5;
TABLESPACE_NAME FILE_ID BLOCK_ID BYTES BLOCKS
------------------------------ ---------- ---------- ---------- ----------
RELATIVE_FNO
------------
T_XFF 5 1408 122683392 14976
5
SQL> select segment_name,segment_type,owner from dba_segments where header_file=5;
SEGMENT_NAME
--------------------------------------------------------------------------------
SEGMENT_TYPE OWNER
------------------ ------------------------------
5.130
TEMPORARY SYS
清理临时段,彻底删除segment header异常对象删除后遗症
SQL> exec dbms_space_admin.segment_corrupt('T_XFF',5,130);
PL/SQL procedure successfully completed.
SQL> exec dbms_space_admin.segment_drop_corrupt('T_XFF',5,130);
PL/SQL procedure successfully completed.
SQL> exec DBMS_SPACE_ADMIN.TABLESPACE_REBUILD_BITMAPS ('T_XFF');
PL/SQL procedure successfully completed.
SQL> select segment_name,segment_type,owner from dba_segments where header_file=5;
no rows selected
SQL> select * from dba_free_space where file_id=5;
TABLESPACE_NAME FILE_ID BLOCK_ID BYTES BLOCKS
------------------------------ ---------- ---------- ---------- ----------
RELATIVE_FNO
------------
T_XFF 5 128 133169152 16256
5
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