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UNDO操作和REDO操作各做些什么事情？
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更多 “UNDO操作和REDO操作各做些什么事情？” 相关考题
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● 对于事务故障的恢复，下列描述正确的是 （48） 。（48）A. 事务故障的恢复不需要访问日志文件B. 事务故障恢复时需要REDO 已提交的事务C. 事务故障恢复时需要正向扫描日志，对该事务进行UNDO 操作D. 事务故障恢复时需要反向扫描日志，对该事务进行UNDO 操作
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下面哪些命令具有还原操作的作用()A. Revert(回复)B. Undo / Redo(还原/重做)C. Step Forward / Step Backward(向前一步骤/向后一步骤)D. Purge(清除)
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
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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
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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
考题
对于事务故障的恢复，下列描述正确的是(70)。A.事务故障的恢复不需要访问日志文件B.事务故障恢复时需要REDO已提交的事务C.事务故障恢复时需要正向扫描日志，对该事务进行UNDO操作D.事务故障恢复时需要反向扫描日志，对该事务进行UNDO操作
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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
考题
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？（）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
考题
You are maintaining your OLTP database in Oracle10g. While observing the performance of the database， you find that the log switch occurs more than once for every 20 minutes， affecting the database performance. Which factor is responsible for frequent log switches？（） A、the value of the UNDO_RETENTION initialization parameterB、the value of the optimal redo log file size provided by the Redo Logfile Size AdvisorC、the online redo log files sizeD、the number of redo log members in a group
考题
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
考题
多选题Which two operations require undo data？（）Acommitting a transactionBrolling back a transactionCrecovering from failed transactionsDrecording a transaction to redo log filesErolling forward during instance recovery
考题
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
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