Answering Structured Queries on Unstructured Data

There is growing number of applications that require access to both structured and unstructured data. Such collections of data have been referred to as dataspaces, and Dataspace Support Platforms (DSSPs) were proposed to offer several services over dataspaces, including search and query, source discovery and categorization, indexing and some forms of recovery. One of the key services of a DSSP is to provide seamless querying on the structured and unstructured data. Querying each kind of data in isolation has been the main subject of study for the fields of databases and information retrieval. Recently the database community has studied the problem of answering keyword queries on structured data such as relational data or XML data. The only combination that has not been fully explored is answering structured queries on unstructured data. This paper explores an approach in which we carefully construct a keyword query from a given structured query, and submit the query to the underlying engine (e.g., a web-search engine) for querying unstructured data. We take the first step towards extracting keywords from structured queries even without domain knowledge and propose several directions we can explore to improve keyword extraction when domain knowledge exists. The experimental results show that our algorithm works fairly well for a large number of datasets from various domains.