# 6.27. ODPI-C Enumeration dpiSubscrQOS

This enumeration identifies the quality of service flags for sending notifications to subscriptions.

Value | Description
--- | ---
DPI_SUBSCR_QOS_BEST_EFFORT | Perform query notification in best effort mode which may result in notifications being sent when the query has not in fact changed. This is needed for complex queries that cannot be registered in guaranteed mode.
DPI_SUBSCR_QOS_DEREG_NFY | When the notification has been received, the subscription is removed.
DPI_SUBSCR_QOS_QUERY | Perform query notification instead of database change notification. Notification is done in guaranteed mode which guarantees that the query has in fact changed.
DPI_SUBSCR_QOS_RELIABLE | Notifications are sent reliably. If the database fails, the notifications are not lost. This is not supported for nonpersistent queues or buffered messaging.
DPI_SUBSCR_QOS_ROWIDS | Information on the rows affected by the database or query change is sent along with the notification.