V$ARCHIVE_GAP

V$ARCHIVE_GAP displays information about archive gaps on a standby database. This view can be used to find out the current archive gap that is blocking recovery for the current recovery incarnation.

Column	Datatype	Description
THREAD#	NUMBER	Thread number of the missing archived redo log files. The number is 1 for a single instance. For Oracle Real Application Clusters, this column will contain different numbers.
LOW_SEQUENCE#	NUMBER	Lowest sequence number of the log files received on the standby system
HIGH_SEQUENCE#	NUMBER	Highest sequence number of the log files received on the standby system
CON_ID	NUMBER	The ID of the container to which the data pertains. Possible values include: 0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs. 1: This value is used for rows containing data that pertain to only the root n: Where n is the applicable container ID for the rows containing data