Answers to Review Questions - OCP: Oracle Database 12c Administrator Certified Professional - page 664

18. E. The V$ARCHIVED_LOG view provides a list of each online redo log sequence num-
ber of that log file and if that log file has been archived. Recall that the online redo
logs are used in a circular fashion. Each time an online redo log is used, a sequence
number is assigned to the data being stored in that redo log. When the redo log file
is switched, the redo log will be archived if the database is in ARCHIVELOG mode.
The sequence number of that instance of the log file is what keeps the log file unique.
When the online redo log is used again, it will be overwritten and a new sequence will
be assigned to it. Thus, once an online redo log is overwritten, the only way to restore
data contained in the previous redo log incarnation is to use the archived redo logs.
19. A, C. Previous to Oracle Database 12 c , the database generally used a multiprocess
architecture (with some exceptions). Oracle Database 12 c provides the ability to use
either a multiprocess architecture or a multithreaded architecture.
20. D. There is no ORCL process in the Oracle Database.
Chapter 2: Performing Oracle
User-Managed Database Recoveries
1. B. Since the database is in NOARCHIVELOG mode, loss of a data file is going to
require the recovery of the entire database. Therefore, you will need to shut down the
database and restore it from the last cold backup along with the online redo logs and
control files. You can then restart the database.
2. D. When you discover that you have lost an online redo log, and if the database is still
up, the first action should be to checkpoint the database. This can serve to reduce the
overall risk of data loss. After you checkpoint the database, you can then attempt to
clear the online redo log. A backup afterward is highly recommended.
3. D. First, you would restore the missing data files. Notice in the question that there are
two data files that were lost. Next, you would mount the database, and then you would
recover the SYSTEM tablespace. Since it is the SYSTEM tablespace, you would not be able
to open the database first. Then you would open the database with the ALTER DATABASE
OPEN command.
4. E. If you lose one or more control files but at least one remains, you should shut down
the database. Then use any remaining control file as the source to create new control-
file copies for the control files that were lost. Then restart the database. No recovery is
required in this situation.
5. A, B, D. You will need to have the database data files, the control files,
and the online redo logs in place to be able to restore the database when it's
in NOARCHIVELOG mode.