Immediately after adding a new disk to or removing an existing disk from an ASM instance, you find that the performance of the database goes down initially until the time the addition or removal process is completed, and then gradually becomes normal.
Which two activities would you perform to maintain a consistent performance of the database while adding or removing disks?（）

You upgraded from a previous Oracle database version to Oracle Database version to Oracle Database12c. Your database supports a mixed workload. During the day, lots of insert, update, and deleteoperations are performed. At night, Extract, Transform, Load (ETL) and batch reporting jobs are run.
The ETL jobs perform certain database operations using two or more concurrent sessions.After the upgrade, you notice that the performance of ETL jobs has degraded. To ascertain the cause ofperformance degradation, you want to collect basic statistics such as the level of parallelism, totaldatabase time, and the number of I/O requests for the ETL jobs.
How do you accomplish this?（）

You are an administrator of a switched network and your goal is to reduce some of the administrative overhead on your network. You plan on achieving this by configuring a new VLAN for each department in your network. However, you need to share the VLAN information across numerous switches throughout your network.
Which of the following would allow you accomplish this?（）

The database administrator of your company created a public synonym called HR for the HUMAN_RESOURCES table of the GENERAL schema, because many users frequently use this table. As a user of the database, you created a table called HR in your schema.
What happens when you execute this query?（）