多选题Which operations require undo data（）ACommitting a transactionBFlashing back a transactionCRecovering a failed transactionDRunning a read-consistent queryEChanging a tablespace status from READ ONLY to READ WRITE

第1题：

ENCRYPT_TS is an encrypted tablespace that contains tables with data. Which statement is true regarding the effect of queries and data manipulation language (DML) statements on the encrypted data in the tables?（）

• A、The data is decrypted during SORT and JOIN operations.
• B、The data remains encrypted when it is read into memory.
• C、The data remains encrypted when it is stored in the redo logs.
• D、The data remains encrypted in the UNDO tablespace provided that the UNDO tablespace was created with the encryption option enabled.

第2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3题：

第4题：

Your database contains a temporary tablespace， index tablespace， undo tablespace， and a read-only tablespace apart from the SYSTEM and SYSAUX tablespaces. If a media failure occurs resulting in the loss of any of these tablespaces， which tablespace is NOT required for the database to start？（）

• A、 undo tablespace
• B、 index tablespace
• C、 read-only tablespace
• D、 temporary tablespace

第5题：

One of the tablespaces is read/x7fonly in your database. The loss of all control files forced you to re/x7fcreate the control file.  Which operation do you need to perform after re/x7fcreating the control file and opening the database？（）

• A、drop and re­create the read­only tablespaces
• B、rename the read­only data files to their correct file names
• C、change the tablespace status from read/write to read­only
• D、re­create the read­only tablespace because it is automatically removed

第6题：

Your database is running in NOARCHIVELOG mode with two online redo log files. The SALES table contains sales information for the organization. The SALES table belongs to the SALESTB tablespace.  On Monday， you insert 10 rows into the SALES table. The current log sequence number is 14. You change the tablespace status from READ WRITE to READ ONLY for the SALESTB tablespace. You shut down the database and take a backup of the SALESTB tablespace.   On Tuesday， you start the database. You change the status for the SALESTB tablespace from READ ONLY to READ WRITE. You insert 10 more rows into the SALES table and shut down the database. The current log sequence number is 15.   When you try to open the database on Wednesday morning， you discover that the SALESTB tablespace was lost because of a media failure. Which of the following options is true about recovering the SALES table？（）

• A、 The SALES table cannot be recovered because the database is running in NOARCHIVELOG mode.
• B、 The SALES table can be recovered by restoring the SALESTB tablespace from the backup and performing a media recovery.
• C、 The SALES table can be recovered by restoring the SALESTB tablespace from the backup without performing any media recovery.
• D、 The SALES table can be recovered by restoring the SALESTB tablespace from the backup， but the rows inserted on Tuesday need to be inserted again.

第7题：

You have a read-only tablespace on read-only media. You want to perform a media recovery on the existing data files， but using a backup control file. The backup control file indicates that the status of the read-only tablespace was read/write when the control file was backed up. What should you consider？（）

• A、 take data files from the read-only tablespace offline before performing a recovery
• B、 recovery using backup control file is not possible， so restore all the files from the last full database backup， and then open the database
• C、 drop the read-only tablespace and re-create the tablespace after recovery
• D、 perform a recovery； status of the tablespace in control file will be changed automatically

第8题：

第9题：

Due to media failure you lost one of the data files belonging to the USERS tablespace， and the tablespace is not available to use. Which statement regarding the status of the database is true？（）

• A、The database remains open.
• B、The database gets dismounted.
• C、The database becomes read only.
• D、The database instance gets aborted.
• E、The database gets shut down automatically.
• F、The status of the database depends on the status of the USERS tablespace.

第10题：

You have a read/x7fonly tablespace on read/x7fonly media. You want to perform a media recovery on the existing data files， but using a backup control file. The backup control file indicates that the status of the read/x7fonly tablespace was read/write when the control file was backed up. What should you consider？（）

• A、drop the read­only tablespace and re­create the tablespace after recovery
• B、take data files from the read­only tablespace offline before performing a recovery
• C、perform a recovery; status of the tablespace in control file will be changed automatically
• D、recovery using backup control file is not possible， so restore all the files from the last full database backup， and then open the database