dba_segments.segment_type

SEGMENT_TYPE VARCHAR2(18)   Type of segment:

    NESTED TABLE           ---  嵌套表段

    TABLE                       ---  堆表段

    TABLE PARTITION        ---  表分区段

    CLUSTER              ---  簇表段

    LOBINDEX                     ---  大对象索引段

    INDEX                           ---  索引段

    INDEX PARTITION        ---  索引分区段

    LOBSEGMENT               ---  大对象段

    TABLE SUBPARTITION  ---  表子分区段

    INDEX SUBPARTITION ---  索引子分区段

    LOB PARTITION            ---  大对象分区段

    LOB SUBPARTITION     ---  大对象子分区段

    ROLLBACK                    ---  回滚段

    TYPE2 UNDO                ---  重做段

    DEFERRED ROLLBACK  ---  延迟回滚段

    TEMPORARY                 ---  临时段

    CACHE                          ---  缓存段

    SPACE HEADER            ---  空间头段

    UNDEFINED                 ---  未定义

    

只要是上面列出的类型段，分配其中的块都有可能出现损坏。

    IO硬件/固件的损坏

    操作系统问题

    数据库问题

    对非FORCELOGGING库的段NOLOGGING或UNRECOVERABLE操作进行恢复

决定损坏受影响的区和判断损坏是持久还是临时的

替换或离开任何错误或怀疑的硬件环境

判断哪些数据库对象受影响

选择合适的数据库恢复或数据保留策略

由于NOLOGGING或UNRECOVERABLE的损坏

    如果对象使用NOLOGGING或UNRECOVERABLE选择，对象所在数据文件进行恢复的话，

涉及对象会报坏块ORA-1578错误，在8i之后ORA-26040错误会产生。

     Recovery操作无法恢复NOLOGGING的数据

     对象块中没有数据会无法挽回

块损坏类型包括物理损坏和逻辑损坏

    Bad header - the beginning of the block (cache header) is corrupt with invalid values

    The block is Fractured/Incomplete - header and footer of the block do not match

    The block checksum is invalid

    The block is misplaced

    Zeroed out blocks Note 1545366.1

This is when block contains a valid checksum and the structure below the beginning of the block is corrupt (Block content is corrupt). It may cause different ORA-600 errors.

The detailed corruption description for Logical Corruptions are not normally printed in the alert.log. DBVerify will report what is logically corrupted in the block.

Corruption Examples are:

    row locked by non-existent transaction - ORA-600 [4512], etc

    the amount of space used is not equal to block size

    avsp bad

    etc.

A corrupt block is a block that has been changed so that it differs from what Oracle Database expects to find. This note covers three data block corruption types:

    In a physical block corruption, which is also called a media corruption, the database does not recognize the block at all: the checksum is invalid, the block contains all zeros, the header and footer of the block do not match or one of the key data block data structure is incorrect such as the data block address (DBA).

    In a logical block corruption, the contents of the block are physically sound and pass the physical block checks; however the block can be logically inconsistent. Examples of logical corruption include corruption of a row piece or index entry.     

    Block corruptions caused by stray writes, lost writes or misdirected writes can also cause havoc to your database availability. The data block may be physically or logically correct but in this case the block’s content is older or stale or in the wrong location.

Block corruptions can also be divided into interblock corruption and intrablock corruption:

    In intrablock corruption, the corruption occurs in the block itself and can be either a physical or a logical corruption.

    In an interblock corruption, the corruption occurs between blocks and can only be a logical corruption.

图例显示分类

http://s9/mw690/002oQdHJgy71p3dTYmsd8&690

   

2.尽可能多的记录坏块信息，AFN,RFN,FILE,Block#,object,object_type

2.在有备份的情况下采用blockrecover,datafile,database级别的恢复，BR但是只针对普通表块，无法对系统块操作；

通过dbms_repair..skip_corrpt_blocks(owner,tab) 跳过表上坏块备份数据

通过10231事件设置跳过表上坏块备份数据

索引数据可以进行索引重建

SELECT dbms_rowid.rowid_created(1,OID,RFN,BL,0) low_rowid FROM dual;

SELECT dbms_rowid.rowid_created(1,OID,RFN,BL 1,0) high_rowid FROM dual;

INSERT INTO TABLE  SELECT * FROM table WHERE rowid high_rowid

如果是NOT NULL字段可以

SELECT /index_ffs()/ FROM table WHERE rowid high_rowid;

NULL字段

SELECT /index()/ FROM table WHERE rowid high_rowid;