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Research On The Cache And Query Technology In Wide Area Sensor Databases

Posted on:2007-05-05Degree:MasterType:Thesis
Country:ChinaCandidate:S Z ZhangFull Text:PDF
GTID:2178360212995505Subject:Computer application technology
Abstract/Summary:PDF Full Text Request
Wide area sensor databases are an internationally hotspot research area at present. The sensor network provides a brand-new platform and foundation structure for people. It allows people to deploy many kinds of application systems in a broader scope and network.At present, it is still in the state of beginning of the research work in that domain. And the technical aspects are not mature, which still have some shortcomings. The current situation of wide area sensor databases is analyzed in detail. The cache and query processing technology in wide area sensor databases are researched from a completely new perspective in this paper.Firstly, the cache technology in wide area sensor databases is introduced. Focused on the problem of storing the node data repeatedly, the new method of storing node data is proposed. Because the capacity of cache is limited and the cache algorithm has certain limitations. That causes low cache hit rate and a waste of the system resources. The architecture of combining cache technology with prefetch technology is proposed and then every module and its algorithms are analyzed in detail.Secondly, the query processing technology in wide area sensor databases is researched in this paper. Focused on the queries whose nesting depth is bigger than 0, the method of query equal decomposition is proposed. The query equal decomposition theorem and algorithm are given and the correctness of the algorithm is proved.Thirdly, focusing on the query redundancy problem among multiple queries, the method of identifying and eliminating the common sub-query operations among the multiple queries through building the query attribute graph is proposed and the multiple queries processing architecture is designed.Finally, the simulation of Parking Space Finder service is built and all the algorithms that proposed in this paper are certified by experiment. That lays the foundation for a deep research in the future.
Keywords/Search Tags:Sensor network, Wide area sensor databases, Cache, Prefetch, XPath, Data redundancy, Nesting depth, Multiple queries processing
PDF Full Text Request
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