Oraclecorruptblock（坏块）详解(4)

当SORT_AREA_SIZE 指定的sort 空间不够时，会在磁盘上创建一个temporary segments来作为排序使用。 建议每个用户指定自己的temporary tablespace。

adding a temporary tablespace to a tablespace group: examplethe following statement creates the tbs_temp_02 temporary tablespace as a member of the tbs_grp_01 tablespace group. if the tablespace group does not already exist, then oracle database creates it during execution of this statement:。a permanent locally managed tablespace can contain only permanent objects. if you need a locally managed tablespace to store temporary objects, for example, if you will assign it as a user's temporary tablespace, then use the temporary_tablespace_clause.。creating a temporary tablespace: examplethis statement shows how the temporary tablespace that serves as the default temporary tablespace for database users in the sample database was created:。

ALTERUSER user_name TEMPORARY TABLESPACE TEMP;

This way, the temporary segments created by any user will be in the TEMP tablespaceand it provides easy manageability.

Detection

· Usually thissegment is never corrupted since they are reformatted every time they get used

Repair

· Tempsegments are reused frequently

· If problempersists, either move or drop and recreate the temp tablespace

4.3.6 Data/Index blocks (DATA/INDEX tablespace)

Whena data block is corrupted, when it belongs to a table segment, cluster segmentor an index segment, the detection mechanisms are the same:

datablock的corrupt可以出现在table segmentlogical dump，cluster segment和index segment。

可以通过以下方法来检测corruption：

（1）DBVERIFY can be used to detect the corrupted blocks in thedata file

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（4）Events 10210, 10211, 10212 can be set in the INIT.ORA file todetect software corrupt blocks. When there is a corruption in a block, it is not detecteduntil the block is being updated. So any SELECTs on a corrupted block is executed until it is marked assoftware corrupt. When the events areset in the INIT.ORA, the blocks are checked for integrity by comparing certaindata structures and once there is an inconsistency found, the seq or the sequence of the block is set to 0 in theblock header representing that the block is software corrupt.

The events can be set as follows:

event= “10210 trace name context forever, level 10” (for data blocks)

alter session set events '10053 trace name context forever'。oradebug event 10053 trace name context forever, level 1。oradebug event 10053 trace name context off。

alter session set events '10053 trace name context forever'。oradebug event 10053 trace name context forever, level 1。oradebug event 10053 trace name context off。

（5）Users receiving ORA-1578 when trying to access an object. The query from DBA_EXTENTS given in pg# 30shows that the error is on a table, cluster or index in the data tablespace,SQL语句如下：

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（6）ALERT.LOG shows ORA-1578 or ORA-600s with the first argument in therange of 2000 to 8000

4.3.6.1 Tables

Whena data block is corrupted in a table, it should be understood that the data inthe corrupted block is lost. The onlyway to not lose any data from the table is to restore from a valid backup andrecover until a point in time before the corruption occurred.

datablock 坏块通常意味着数据的丢失，如果要保证没有数据丢失，需要通过有效的备份进行恢复。这块参考1.4节。

方法一：Event method

Event10231 can be set to skip corrupted blocks on full table scans in the INIT.ORAfile. The object can be exported aftersetting this event. This is notguaranteed to work for every kind of corruption.

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