Abstract: Two approaches are proposed to process the constraint event stream with uncertain timestamps. The query processing approach based on possible worlds can obtain the results by scanning the possible worlds according to the semantic of the constraint events. The query processing approach based on constraint event priority calculates the joint probability density of event timestamps, furtherly, calculates the marginal probability density of events in the composited query, and finally processes the query according to the query processing technology for the uncertain timestamp events. Experiments verify that both the query processing approaches for constraint event streams with uncertain timestamps are effective, and due to the smaller possible worlds, the query processing approach based on constraint event priority is more efficient than the query processing approach based on possible worlds.

Key words: constraint event, uncertain timestamp, complex event processing, event stream