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042-144

原创 Linux操作系统 作者:jbymy2000 时间:2012-03-15 15:48:18 0 删除 编辑
144. Which two statements regarding the LOGGING clause of the CREATE TABLESPACE... statement are correct? (Choose two.)
A) This clause is not valid for a temporary or undo tablespace.
B) If the tablespace is in the NOLOGGING mode, no operation on the tablespace will generate redo.
C) The tablespace will be in the NOLOGGING mode by default, if not specified while creating a tablespace.
D) The tablespace-level logging attribute can be overridden by logging specifications at the table, index, materialized view, materialized view log, and partition levels.
答案:AD
都是很基础的概念性问题,临时表空间都是nologging的
logging clause
这个子句声明这个表空间上所有的用户对象的日志属性(缺省是logging),包括表,索引,分区,物化视图,物化视图上的索引,分区。
FORCE LOGGING
使用这个子句指出表空间进入强制日志模式。此时,系统将记录表空间上对象的所有改变,除了临时段的改变。这个参数高于对象的nologging选项。
注意:设置这个参数在临时表空间和回滚表空间中不能使用这个选项。
With the given CREATE TABLESPACE statement, the tablespace created can be changed to the LOGGING mode, and using the NOLOGGING clause in the statement will save space in the redo log files.
The tablespace created using the NOLOGGING clause can be changed to the NOLOGGING mode by using the ALTER TABLESPACE statement with the NOLOGGING clause. When a tablespace is created by using the NOLOGGING clause,the operations in the tablespace will not generate any redo data. As a result, space will be saved in the redo log files.
The objects created using the NOLOGGING clause cannot be recovered because no redo is generated for these objects.
Therefore, the NOLOGGING clause should be used with objects that can be easily re-created without the redo data.
The NOLOGGING clause is not valid for a temporary or undo tablespace.
D选项是说在表空间级别的logging选项没有在表、视图等的级别高

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