XML数据流上的TOP-K关键字查询处理-计算机科学与技术专业论文.docxVIP

哈尔 哈尔滨工业大学工学硕士学位论文 – – II – 由结构的启发式算法；通过模拟实验表明算法具有很高的效率和可扩展性，并 验证了该算法的有效性。 关键词： XML数据流；关键字查询；TOP-K查询；skyline查询 – – III – Abstract XML has become the def acto standard for various kinds of data over the internet because of its flexibility and expandability. In some application, XML data is in streaming form, which is continuous coming XML fragments. We use the term XML Stream to refer to XML fragments in streaming form. The applications of XML stream include information scribe/publish on internet, email detection and so on. Since XML streams may come from various and dynamic data sources, this search model is complicated for most users. Thus querying XML streams with keywords without schema information is in great demand. In this paper we focus on keyword search on XML streams. The keyword search on XML streams is that given a set of keywords Q, the set of all the XML fragments in the XML streams with each of them containing all the keywords is retrieved. In order to process TOP-K keyword queries on XML streams efficiently, we propose three novel kinds of TOP-K keyword queries on XML streams. Efficient algorithms are also presented to process these queries. The contributions of this paper can be summarized as following: A query processing method based on ranking is presented to process TOP-K keyword queries on XML streams. In details, we propose a novel ranking strategy RSR to efficiently evaluate the relevance of queries; a stack-based algorithm TKS is presented to process TOP-K keyword search over XML streams efficiently, both the time complex- ity and the space complexity of TKS are analyzed; a filtering method is presented to improve the efficiency and save storing space; experimental results show that such query processing method has high efficiency and scalability. A query processing method based on skyline is presented to process TOP-K keyword queries on XML streams. In details, Skyline is applied to keyword query on XML streams for the cases that the same