document: Sailer : an effective search engine for unified retrieval of heterogeneous xml and web documents This paper studies the problem of unified ranked retrieval of heterogeneous XML documents and Web data . We propose an effective search engine called Sailer to adaptively and versatilely answer keyword queries over the heterogenous data . We model the Web pages and XML documents as graphs . We propose the concept of pivotal trees to effectively answer keyword queries and present an effective method to identify the top-k pivotal trees with the highest ranks from the graphs . Moreover , we propose effective indexes to facilitate the effective unified ranked retrieval . We have conducted an extensive experimental study using real datasets , and the experimental results show that Sailer achieves both high search efficiency and accuracy , and outperforms the existing approaches significantly .
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