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arXiv 1208.0075cs.DB
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Web中隐藏数据库的最优搜索算法

Optimal Algorithms for Crawling a Hidden Database in the Web

Cheng Sheng, Nan Zhang, Yufei Tao, Xin Jin

摘要:

隐藏数据库是指组织通过允许用户通过搜索界面发出查询来在Web上访问的数据集。换句话说,从这样的源的数据采集不是通过遵循静态超链接。相反,通过查询接口并读取动态生成的结果页面来获取数据。这一点,与其他事实,如界面可能只回答部分查询,已阻止隐藏的数据库被有效地爬行现有的搜索引擎。本文通过给出从隐藏数据库中提取所有元组的算法来解决这个问题。我们的算法是可证明有效的,也就是说,他们只执行少量的查询,即使在最坏的情况下完成任务。我们还建立了理论结果表明,这些算法是渐近最优的-即,不可能将它们的效率提高超过一个常数。我们的上限和下限结果的推导揭示了显着的洞察到的基本问题的特点。大量的实验证实了所提出的技术在所有真实数据集上都能很好地工作。

英文摘要:

A hidden database refers to a dataset that an organization makes accessible on the web by allowing users to issue queries through a search interface. In other words, data acquisition from such a source is not by following static hyper-links. Instead, data are obtained by querying the interface, and reading the result page dynamically generated. This, with other facts such as the interface may answer a query only partially, has prevented hidden databases from being crawled effectively by existing search engines. This paper remedies the problem by giving algorithms to extract all the tuples from a hidden database. Our algorithms are provably efficient, namely, they accomplish the task by performing only a small number of queries, even in the worst case. We also establish theoretical results indicating that these algorithms are asymptotically optimal -- i.e., it is impossible to improve their efficiency by more than a constant factor. The derivation of our upper and lower bound results reveals significant insight into the characteristics of the underlying problem. Extensive experiments confirm the proposed techniques work very well on all the real datasets examined.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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