A query processing approach based on window semantics in data stream system

  • Authors:
  • Baoyan Song;Shanshan Wu;Feng Yuan;Ge Yu

  • Affiliations:
  • School of Computer Science and Technology, LiaoNing University, China;School of Computer Science and Engineering, Northeastern University, China;School of Computer Science and Engineering, Northeastern University, China;School of Computer Science and Engineering, Northeastern University, China

  • Venue:
  • ASIAN'05 Proceedings of the 10th Asian Computing Science conference on Advances in computer science: data management on the web
  • Year:
  • 2005

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Abstract

Since data streams are continuous, unbounded and real-time, continuous queries over data streams are generally based on windows. Windows placed on data streams are maintained by operators themselves for a query in most DSMSs. However, some operators can't maintain the windows properly, and a lot of redundancy and inconsistency may be incurred because the tuples are heavily copied and operators interfere with each other. In this paper, we thoroughly discuss the query processing mechanism based on windows and analyze the window semantics in a query sentence, then propose a query processing approach MullayerQuery that abstract windows into two types, stream window and operator windows. A strategy and some algorithms are given to keep the consistency among windows in a query. The experiments show MullayerQuery can't only maintain the query semantics, but also implement to share data in multiple queries as well as decrease the usage of memory. MullayerQuery has been carried out in a prototype system-RealStream that is a DSMS for real-time embedded applications.