1999 · 217 citations · 16 references
Data integration systems must handle web‑of‑data sources, but existing models fail to capture linked data relationships and the need for path navigation. The authors propose a language for modeling such web‑of‑data sources. They present a sound and complete algorithm that reformulates user queries into source‑level queries and generates execution plans that both query and navigate the sources. The language is shown to be expressively sufficient, while any minor extensions would render query answering intractable.
We consider the problem of building data integration systems when the data sources are webs of data, rather than sets of relations. Previous approaches to modeling data sources are inappropriate in this context because they do not capture the relationships between linked data and the need to navigate through paths in the data source in order to obtain the data. We describe a language for modeling data sources in this new context. We show that our language has the required expressive power, and that minor extensions to it would make query answering intractable. We provide a sound and complete algorithm for reformulating a user query into a query over the data sources, and we show how to create query execution plans that both query and navigate the data sources.
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