单选题Users in your PROD database complain about the slow response of the transactions. While investigating the reason， you find that the transactions are waiting for the undo segments to be available， and undo retention has been set to zero. What would you 

第1题：

You executed the following query：  SELECT operation， undo_sql， table_name FROM flashback_transaction_query； Which statement is correct regarding the query output？（）

• A、 It would return information regarding only the last committed transaction.
• B、 It would return only the active transactions in all the undo segments in the database.
• C、 It would return only the committed transactions in all the undo segments in the database.
• D、 It would return both active and committed transactions in all the undo segments in the database.
• E、 It would return information regarding the transactions that began and were committed in the last 30 minutes.

第2题：

You work as a database administrator for Certkiller .com. Users complain that their query is taking a long time to complete. You suspect the database buffer cache size to be the reason， and you define an alert to be generated when the buffer cache hit metric goes below 85%. When you observe the dynamic performance views， you find that the buffer cache hit ratio is 81% but no alerts are being generated.  What could be the reason for this problem？（）

• A、The advisory memory has been turned off.
• B、The DB_CACHE_ADVICE parameter has been set to OFF in the parameter file.
• C、The STATISTICS_LEVEL parameter has been set to BASIC in the parameter file.
• D、The TIMED_STATISTICS parameter has been set to FALSE in the parameter file.
• E、The STATISTICS_LEVEL parameter has been set to TYPICAL in the parameter file.

第3题：

You are maintaining your database in Oracle10g. You set the value of the UNDO_RETENTION initialization parameter to zero in the initialization parameter file. What will be the impact of specifying this setting？（）  

• A、 The database will not start.
• B、 The database will start but will not retain the undo data in the undo segment.
• C、 The database will start， and the undo segment will contain the undo data for at least one hour.
• D、 The database will start， and the undo segment will retain the undo data for at least 15 minutes.

第4题：

Your database is running under automatic undo management and the UNDO_RETENTION parameter is set to 900 sec. You executed the following command to enable retention guarantee：  SQL> ALTER TABLESPACE undotbs1 RETENTION GUARANTEE;  What effect would this statement have on the database？（）

• A、The extents in undo tablespace retain data until the next full database backup.
• B、The extents containing committed data in the undo tablespace are never overwritten.
• C、The extents which no longer contain uncommitted data in the undo tablespace are not overwritten for at least15 minutes.
• D、The extents containing committed data in the undo tablespace are not overwritten until the instance  is shut down.

第5题：

In your database， UNDO_RETENTION has been set to 600 sec and UNDO tablespace is configured for RETENTION GUARANTEE. Which statement regarding RETENTION GUARANTEE is true？ （）

• A、Undo data is retained until the next full database backup.
• B、No committed undo data will be overwritten for 10 minutes.
• C、Committed undo data will be kept forever if not overwritten within 600 seconds.
• D、Guarantees that requested undo information are available until the instance is shut down.

第6题：

You need to ensure that the database users should be able to use the various flashback query features in order to go back in time by four hours. What would you do to achieve this?（）

• A、set SQL_TRACE=True 
• B、set UNDO_RETENTION=14400 
• C、set FAST_START_MTTR_TARGET=240 
• D、set LOG_CHECKPOINT_INTERVAL=240 
• E、set DB_FLASHBACK_RETENTION_TARGET=14400 
• F、set the RETENTION GUARANTEE clause for the undo tablespace

第7题：

You work as a database administrator for Certkiller .com. Users in the Certkiller PROD database complain about the slow response when accessing the database. In the Active Session Waiting： Configuration page you find that the majority of the wait time is for the redo log buffer.Further investigation using the Run Queue graph and operating system tools reveals that the redo log files are on the same disks， and that the disk I/O for the redo log files is the reason for the performance degradation.  Which two actions would you take to gain performance？（）

• A、Increase the size of redo log files
• B、Increase the size of redo log buffer
• C、Increase the number of redo log files
• D、Place the redo log files on a separate disk
• E、Decrease the number of redo log groups to two
• F、Increate the number Log Writer （LGWR） process

第8题：

Users in your PROD database complain about the slow response of the transactions. While investigating the reason， you find that the transactions are waiting for the undo segments to be available， and undo retention has been set to zero. What would you do to overcome this problem？（）

• A、increase the undo retention
• B、create more undo segments
• C、create another undo tablespace
• D、increase the size of the undo tablespace

第9题：

You work as a database administrator for Certkiller .com. You want to create your database with the automatic undo management feature enable.Which two tasks must you perform to achieve this？（）

• A、Set the UNDO_RETENTION parameter to AUTO.
• B、Create an initial undo segment in undotablespace.
• C、Set the UNDO_RETENTION parameter to 900 or more
• D、Set the initialization parameter UNDO_MANAGEMENT to AUTO
• E、Set the UNDO_MANAGEMENT parameter to the name of an undotablespace

第10题：

Initially， for the Automatic Workload Repository （AWR） statistics， the retention period is set to 7 days， the collection interval is set to 30 minutes and the collection level is set to Typical in your production database.  You have been using the Memory Advisor for the last three months to generate recommendations for tuning memory components. However， when you observe the Memory Advisor on a Friday， you find that the statistics are available only for two days， Thursday and Friday， of that week.  What would have caused the statistics to be removed？（）

• A、On Wednesday， the statistics have been purged.
• B、On Wednesday， the retention period has been set to zero.
• C、On Wednesday， the collection interval has been set to zero.
• D、On Wednesday， the collection level has been changed to All.
• E、On Wednesday， the retention period has been set to one day.
• F、On Wednesday， the retention period has been set to two days.
• G、On Wednesday， the collection level has been changed to Typical.
• H、On Wednesday， the collection interval has been set to 1440 minutes.