Sketching asynchronous streams over a sliding window

Srikanta Tirthapura, Bojian Xu, Costas Busch

Research output: Chapter in Book/Report/Conference proceedingConference contribution

32 Scopus citations

Abstract

We study the problem of maintaining sketches of recent elements of a data stream. Motivated by applications involving network data, we consider streams that are asynchronous, in which the observed order of data is not the same as the time order in which the data was generated. The notion of recent elements of a stream is modeled by the sliding timestamp window, which is the set of elements with timestamps that are close to the current time. We design algorithms for maintaining sketches of all elements within the sliding timestamp window that can give provably accurate estimates of two basic aggregates, the sum and the median, of a stream of numbers. The space taken by the sketches, the time needed for querying the sketch, and the time for inserting new elements into the sketch are all polylog with respect to the maximum window size and the values of the data items in the window. Our sketches can be easily combined in a loss-less and compact way, making them useful for distributed computations over data streams. Previous works on sketching recent elements of a data stream have all considered the more restrictive scenario of synchronous streams, where the observed order of data is the same as the time order in which the data was generated. Our notion of recency of elements is more general than that studied in previous work, and thus our sketches are more robust to network delays and asynchrony.

Original languageEnglish (US)
Title of host publicationProceedings of the 25th Annual ACM Symposium on Principles of Distributed Computing 2006
PublisherAssociation for Computing Machinery (ACM)
Pages82-91
Number of pages10
ISBN (Print)1595933840, 9781595933843
DOIs
StatePublished - 2006
Externally publishedYes
Event25th Annual ACM Symposium on Principles of Distributed Computing 2006 - Denver, CO, United States
Duration: Jul 23 2006Jul 26 2006

Publication series

NameProceedings of the Annual ACM Symposium on Principles of Distributed Computing
Volume2006

Conference

Conference25th Annual ACM Symposium on Principles of Distributed Computing 2006
CountryUnited States
CityDenver, CO
Period7/23/067/26/06

Keywords

  • Aggregates
  • Asynchronous streams
  • Data stream processing
  • Distributed streams
  • Sketches of streams
  • Sliding windows
  • Union of streams

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture
  • Computer Networks and Communications

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