After performing a clean shut down of the database instance for maintenance, you mount the
database and then execute a command to open the database:
SQL>ALTER DATABASE OPEN;
Which two statements are true? (Choose two.)
A.
The online redo log files and online data files are opened
B.
All the online data files headers are checked for consistency
C.
Instance recovery is performed before opening the database
D.
The path and existence of all the log file members are checked
MOUNT
Mounts the database without opening it. This option is equivalent to the SQL statement ALTER DATABASE MOUNT.
OPEN
Opens the database.
RESETLOGS
Archives the current online redo logs (or up to the last redo record before redo corruption if corruption is found), clears the contents of the online redo logs, and resets the online redo logs to log sequence 1. The RMAN RESETLOGS option is equivalent to the SQL statement ALTER DATABASE OPEN RESETLOGS.
Datafile header
The first block of an Oracle datafile. The file header contains bookkeeping information related to the file, including the checkpoint SCN. Oracle requires media recovery when the checkpoint SCN in the datafile header does not match the file header information stored in the control file.