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Erschienen in:
2006 | OriginalPaper | Buchkapitel
Estimating Aggregate Join Queries over Data Streams Using Discrete Cosine Transform
verfasst von : Zhewei Jiang, Cheng Luo, Wen-Chi Hou, Feng Yan, Qiang Zhu
Erschienen in: Database and Expert Systems Applications
Verlag: Springer Berlin Heidelberg
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Data stream processing is required to be an on-line, one-pass, and time and space efficient process. In this paper, we develop a framework for estimating equi-join query size based on the cosine transform. The discrete cosine transform (DCT) is able to provide concise and accurate representations of data distributions. It can also be updated easily in the presence of insertions and deletions. We have performed analyses and experiments to compare the DCT with sketch-based methods. The experimental results show that given the same amount of space, our method yields more accurate estimates than sketch methods most of the time. Experimental results have also confirmed that the cosine series can be updated quickly to cope with the rapid flow of data.