You performed an incremental level 0 backup of a database:
RMAN > BACKUP INCREMENTAL LEVEL 0 DATABASE;
To enable block change tracking after the incremental level 0 backup, you issued this command:
SQL > ALTER DATABASE ENABLE BLOCK CHANGE TRACKING USING FILE
` /mydir/rman_change_track.f';
To perform an incremental level 1 cumulative backup, you issued this command:
RMAN> BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE;
Which three statements are true?

• A. More than one database block may be read by an incremental backup for a change made to a single block.
• B. The change tracking file must always be backed up when you perform a full database backup.
• C. The incremental level 1 backup that immediately follows the enabling of block change tracking will not read the change tracking file to discover changed blocks.
• D. Backup change tracking will sometimes reduce I/O performed during cumulative incremental backups.
• E. Block change tracking will always reduce I/O performed during cumulative incremental backups.

Which two statements are true regarding constraints?

• A. A constraint can be disabled even if the constraint column contains data.
• B. A column with the unique constraint can contain null values.
• C. All constraints can be defined at the column level as well as the table level.
• D. A constraint is enforced only for the insert operation on a table.
• E. A foreign key cannot contain null values.

You are connected using SQL* Plus to a multitenant container database (CDB) with SYSDBA privileges and execute the following sequence statements:

What is the result of the last SET CONTAINERstatement and why is it so?

• A. It succeeds because the PDB_ADMIN user has the required privileges.
• B. If fails because the SET CONTAINER statement cannot be used with PDB$SEED as the target pluggable database (PDB).
• C. It fails because common users are unable to use the SET CONTAINER statement.
• D. It fails because local users are unable to use the SET CONTAINER statement.

You notice that the performance of your production 24/7 Oracle database significantly degraded.
Sometimes you are not able to connect to the instance because it hangs.
You do not want to restart the database instance.
How can you detect the cause of the degraded performance?

• A. Enable Memory Access Mode, which reads performance data from SGA.
• B. Run Automatic Database Diagnostic Monitor (ADDM) to fetch information from the latest Automatic Workload Repository (AWR) snapshots.
• C. Use emergency monitoring to fetch data directly from SGA analysis.
• D. Run ADDM in diagnostic mode.
• E. Use Active Session History (ASH) data and hang analysis in regular performance monitoring.

Which statement is true regarding the default behavior of the order by clause?

• A. Only those columns that are specified in the select list can be used in the order by clause.
• B. NULL values are not considered at all by the sort operation.
• C. In a character sort, the values are case-sensitive.
• D. Numeric values are displayed from the maximum to the minimum value if they have decimal positions.