An Hybrid Data Stream Summarizing Approach by Sampling and Clustering

Computer systems generate a large amount of data that, in terms of space and time, is very expensive even impossible to store. Besides this, many applications need to keep an historical view of such data in order to provide historical aggregated information, perform data mining tasks or detect anomalous behavior in the computer systems. One solution is to treat the data as streams that can be processed on the fly in order to build historical summaries. Many data summarizing techniques have already been developed such as sampling, clustering, histograms, etc. Some of them have been extended to be applied directly to data streams. This chapter presents a new approach to building such historical summaries of data streams. It is based on a combination of two existing algorithms: StreamSamp and CluStream. The combination takes advantages of the benefits of each algorithm and avoids their drawbacks. Some experiments are presented both on real and synthetic data. These experiments show that the new approach gives better results than using any one of the two mentioned algorithms.