单项选择题

Which statement is true regarding the COALESCE function?（）

A.It can have a maximum of five expressions in a list
B.It returns the highest NOT NULL value in the list for all rows
C.It requires that all expressions in the list must be of the same data type
D.It requires that at least one of the expressions in the list must have a NOT NULL value

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单项选择题

What does the minimize load database parameter mean when backing up a database?（）

A.RMAN will attempt to make the backup run as fast as possible without any IO limitations.
B.RMAN will automatically restrict the number of channels in use to one.
C.RMAN will spread the backup IO over the total duration stated in the backup command.
D.RMAN will skip any datafile that currently is involved in an IO operation. RMAN will retry backing up the datafile later and an error will be raised at the end of the backup if the datafile cannot be backed up.
E.Datafiles will be backed up; those having the lowest current number of IO operations will be backed up first.

单项选择题

What view might you use to try to determine how long a particular backup will take?（）

A.V$SESSION_EVENT
B.V$SESSION
C.V$W0041ITS
D.V$WAITSTAT
E.V$SESSION_LONGOPS

单项选择题

What does it mean if a backup is expired?（）

A.The backup set has exceeded the retention criteria set in RMAN and is eligible for removal.
B.The backup set has one or more invalid blocks in it and is not usable for recovery.
C.The backup set contains one or more tablespaces no longer in the database.
D.The backup set contains one or more missing backup set pieces.
E.The backup set is from a previous version of RMAN and was not upgraded.