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Eager Evaluation of Partial Tree-Pattern Queries on XML Streams

机译：对XML流上的部分树模式查询的热切评估

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摘要

Current streaming applications have stringent requirements on query response time and memory consumption because of the large (possibly unbounded) size of data they handle. Further, known query evaluation algorithms on streaming XML documents focus almost exclusively on tree-pattern queries (TPQs). However recently, requirements for flexible querying of XML data have motivated the introduction of query languages that are more general and flexible than TPQs. These languages are not supported by known algorithms.rnIn this paper, we consider a language which generalizes and strictly contains TPQs. Queries in this language can be represented as dags enhanced with constraints. We explore this representation to design an original polynomial time streaming algorithm for these queries. Our algorithm avoids storing and processing matches of the query dag that do not contribute to new solutions (redundant matches). Its key feature is that it applies an eager evaluation strategy to quickly determine when node matches should be returned as solutions to the user and also to proactively detect redundant matches. We experimentally test its time and space performance. The results show the superiority of the eager algorithm compared to the only known algorithm for this class of queries which is a lazy algorithm.
机译：当前的流应用程序对查询响应时间和内存消耗有严格的要求，因为它们处理的数据量很大（可能是无限的）。此外，关于流XML文档的已知查询评估算法几乎只专注于树型查询（TPQ）。但是，近来，对XML数据进行灵活查询的要求促使引入了比TPQ更通用，更灵活的查询语言。这些语言不受已知算法的支持。在本文中，我们考虑一种可以泛化并严格包含TPQ的语言。可以将这种语言中的查询表示为受约束增强的dag。我们探索这种表示形式，以设计用于这些查询的原始多项式时间流算法。我们的算法避免了存储和处理查询dag的匹配，这些匹配对新的解决方案没有贡献（冗余匹配）。它的关键特性是它采用了一种急切的评估策略，以快速确定何时应将节点匹配作为解决方案返回给用户，并主动检测冗余匹配。我们通过实验来测试其时空性能。结果表明，相比于此类查询的唯一已知算法（即惰性算法），渴望算法的优越性。

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  • 来源
  • 会议地点 Brisbane(AU);Brisbane(AU)
  • 作者

    Dimitri Theodoratos; Xiaoying Wu;

  • 作者单位

    Department of Computer Science, New Jersey Institute of Technology, USA;

    Department of Computer Science, New Jersey Institute of Technology, USA;

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  • 原文格式 PDF
  • 正文语种 eng
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