Sergio Luis Sardi Mergen, Juliana Freire, Carlos A. Heuser. Indexing relations on the web. In Ioana Manolescu, Stefano Spaccapietra, Jens Teubner, Masaru Kitsuregawa, Alain Léger, Felix Naumann, Anastasia Ailamaki, Fatma Özcan, editors, EDBT 2010, 13th International Conference on Extending Database Technology, Lausanne, Switzerland, March 22-26, 2010, Proceedings. Volume 426 of ACM International Conference Proceeding Series, pages 430-440, ACM, 2010. [doi]
There has been a substantial increase in the volume of (semi) structured data on the Web. This opens new opportunities for exploring and querying these data that goes beyond the keyword-based queries traditionally used on the Web. But supporting queries over a very large number of apparently disconnected Web sources is challenging. In this paper we propose index methods that capture both the structure of the sources and connections between them. The indexes are designed for data that is represented as relations, such as HTML tables, and support queries with predicates. We show how associations between overlapping sources are discovered, captured in the indexes, and used to derive query rewritings that join multiple sources. We demonstrate, through an experimental evaluation, that our approach scales to a large number of sources.