Window Update Patterns in Stream Operators

Abstract

Abstract. Continuous queries applied over nonterminating data streams usually specify windows in order to obtain an evolving -yet restricted-set of tuples and thus provide timely results. Among other typical variants, sliding windows are mostly employed in stream processing engines and several advanced techniques have been suggested for their incremental evaluation. In this paper, we set out to study the existence of monotonicrelated semantics in windowing constructs towards a more efficient maintenance of their changing contents. We investigate update patterns observed in common window variants as well as their impact on windowed adaptations of typical operators (like selection, join or aggregation), offering more insight towards design and implementation of stream processing mechanisms. Finally, to demonstrate its significance, this framework is validated for several windowed operations against streaming datasets with simulations at diverse arrival rates and window sizes.

Maintaining consistent results of continuous queries under diverse window specifications

“…Their proposed algebraic extensions distinguish operators with respect to monotonicity, but the model has been devised particularly for synchronizing loosely coupled information systems, without taking into account the real-time characteristics of streaming data. In our work, we develop a generalization of monotonicrelated patterns in windows and carefully investigate their impact on typical query operators in more detail than originally discussed in [25]. Enhancing previous studies, we analyze all frequently used window variants over data streams according to rigorous semantics for a rich set of window types [24].…”

“…We discuss in more detail our ideas from [25] and develop heuristics that can be proven valuable to continuous query evaluation. To the best of our knowledge, ours is the first framework that covers all major window variants and operators, also offering a concrete insight of their intrinsic characteristics.…”

A Model of a System for Stream Data Storage and Analysis Dedicated to Sensor Networks of Embankment Monitoring

“…Future work involves consideration of such problems as efficient spatial indexing of data acquired from different measurement points on the grid of sensor networks. Another problem is the sizing of the sliding windows in order to perform proper scenario analysis [19,20]. This case and its related issues is a topic for further consideration.…”