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

第1题：

Which two operations require undo data？（）

• A、committing a transaction
• B、rolling back a transaction
• C、recovering from failed transactions
• D、recording a transaction to redo log files
• E、rolling forward during instance recovery

第2题：

In the parameter file of your production database， the FAST_START_MTTR_TARGET parameter is set to 300 to optimize instance recovery. While observing the performance of the database during instance recovery， you find that the redo log files are not sized properly to support this activity. Which two sources could you use to determine the optimal size of the redo log files？（）

• A、the V$LOG view
• B、the V$DBFILE view
• C、the V$LOGFILE view
• D、the V$INSTANCE_RECOVERY view
• E、Oracle Enterprise Manager Database Control

第3题：

The instance abnormally terminates because of a power outage.  Which statement is true about redo log filesduring instance recovery（）

• A、Inactive and current redo log files are required to accomplish recovery.
• B、Online and archived redo log files are required to accomplish instance recovery.
• C、All redo log entries after the last checkpoint are applied from redo log files to data files.
• D、All redo log entries recorded in the current redo log file until the checkpoint position are applied to data files

第4题：

The instance abnormally terminates because of a power outage. Which statement is true about redolog files during instance recovery（）

• A、Inactive and current redo log files are required to accomplish recovery.
• B、Online and archived redo log files are required to accomplish instance recovery.
• C、All redo log entries after the last checkpoint are applied from redo log files to data files.
• D、All redo log entries recorded in the current redo log file until the checkpoint position are applied to datafiles.

第5题：

Which three operations require undo data（）

• A、committing a transaction
• B、flashing back a transaction
• C、recovering a failed transaction
• D、running a read-consistent query
• E、changing a tablespace status from READ ONLY to READ WRITE

第6题：

You work as a database administrator for Certkiller .com. One of the user sessions was terminated abnormally in the middle of a transaction. What does Oracle database do to recover it？（）

• A、Uses undo data for roll forward
• B、Uses Flashback Log for recovery
• C、Uses online redo logs to roll back
• D、Uses undo data to roll back the transaction
• E、Uses Recovery Manager （RMAN） to roll back
• F、Uses the System Monitor （SMON） background process to perform instance recovery

第7题：

What advantage would you get if you increase the length of time during which the undo information would be stored in the database？（）

• A、roll back of large transactions
• B、roll forward to redo a transaction
• C、data concurrency for large updates
• D、read consistency for long-running transactions

第8题：

You are in the middle of a transaction updating a very important table. The machine on which a database wasrunning reboots because of power outage. This caused a database instance failure. Which statement is true inthis situation（）

• A、The online redo log files and archived redo log files are required to accomplish the recovery.
• B、The uncommitted transaction will be committed at the next startup of the database instance.
• C、The uncommitted transaction is rolled back automatically at the next opening of the database.
• D、The DBA has to perform the recovery on the database to recover the uncommitted transaction

第9题：

One of the user sessions was terminated abnormally in the middle of a transaction. What does Oracle database do to recover it？（）

• A、uses undo data for roll forward
• B、uses Flashback Log for recovery
• C、uses online redo logs to roll back
• D、uses undo data to roll back the transaction
• E、uses Recovery Manager （RMAN） to roll back
• F、uses the System Monitor （SMON） background process to perform instance recovery

第10题：

Which two statements about Flashback Query are true？（）

• A、It is generated by using the redo log files. 
• B、It helps in row-level recovery from user errors.
• C、It can be performed to recover ALTER TABLE statements 
• D、It fails when undo data pertaining to the transaction is overwritten.
• E、The database has to be opened with the resetlogs option after performing Flashback Query.