问答题什么是UNDO操作和REDO操作？为什么要这样设置？
问答题
什么是UNDO操作和REDO操作？为什么要这样设置？
参考解析
解析：
暂无解析
相关考题：
系统故障恢复的步骤是A．反向扫描日志文件、对每一个更新操作执行逆操作，如此下去B．对每一个更新操作执行逆操作、反向扫描日志文件，如此下去C．正向扫描日志文件、对UNDO队列中的事务进行UNDO处理、对REDO队列中的事务进行REDO处理D．正向扫描日志文件、对REDO队列中的事务进行REDO处理、对UNDO队列中的事务进行UNDO处理
下列系统故障恢复步骤正确的顺序是（ ）。 I．找出故障前已提交的事务，标记为REDO；找出故障时尚未完成的事务，标记为UNDO II．对UNDO队列中的事务做UNDO处理 Ill．对REDO队列中的事务做REDO处理A．I、II、III B．I、III、 IIC．II、III、 I D．III、 II、I
下列系统故障恢复步骤正确的顺序是( )。Ⅰ、找出故障前已提交的事务，标记为REDO，找出故障时尚未完成的事务，标记为UNDOⅡ、对UNDO队列中的事务做REDO处理Ⅲ、对REDO队列中的事务做UNDO处理A．Ⅰ、Ⅱ、ⅢB．Ⅰ、Ⅲ、ⅡC．Ⅱ、Ⅲ、ⅠD．Ⅲ、Ⅱ、Ⅰ
关于检查点技术下面描述正确的是（）A、检查点之后开始故障点之前提交的事务需要undo操作B、检查点技术是为了提高故障恢复效率C、检查点之后开始故障点之前提交的事务需要redo操作D、检查点之前提交的事务不需要redo操作
You started a long transaction. Before committing， you executed a query on one of the tables currently being modified. You received the following error： ORA-01555： snapshot too old How would you prevent such an error in the future？（）A、guarantee undo retentionB、add one more redo log groupC、size the redo log files appropriatelyD、size the UNDO tablespace appropriatelyE、size the SYSTEM tablespace appropriatelyF、configure an appropriate undo retention intervalG、change automatic undo management to manual
多选题Which three pieces of information are considered while deciding the size of the undo tablespace in your database？（）Athe size of an undo blockBthe size of the redo log filesCundo blocks generated per secondDthe size of the database buffer cacheEthe value of the UNDO_RETENTION parameter
多选题You started a long transaction. Before committing， you executed a query on one of the tables currently being modified. You received the following error： ORA-01555： snapshot too old How would you prevent such an error in the future？（）Aguarantee undo retentionBadd one more redo log groupCsize the redo log files appropriatelyDsize the UNDO tablespace appropriatelyEsize the SYSTEM tablespace appropriatelyFconfigure an appropriate undo retention intervalGchange automatic undo management to manual
问答题什么是图层？为什么要设置图层？