When you connect to the list structure and indicate your interest in using list keyrange monitoring, the system allocates a list notification vector. When a list transition occurs for the monitored list, the system updates the associated entry in the list notification vector to reflect the empty or not-empty state of the keyrange according to the established threshold values. The IXLVECTR service provides the interface to the list notification vector. See The List Notification Vector for additional information.

The IXLVECTR service can also be used to alter the size of the list notification vector, and thus change the number of lists that can be monitored. Only one keyrange can be monitored per list.

Under most circumstances, if a list notification vector index is in use for monitoring, a request to stop monitoring should be issued before using the same vector index to start another monitor. With keyrange monitoring, it is not necessary to stop monitoring with an old index before starting monitoring with a new index. With keyrange monitoring, a request to start monitoring causes the vector index in use to be replaced by the new vector index.