Query rewriting with filtering constraints
نویسندگان
چکیده
A database may contain inaccurate information. When querying such a database, one may want to impose filtering constraints so that only answers produced from reasonable subsets of the data are presented. We call the problem of producing these answers with respect to a set of filtering constraints the Reasonable Query Answers (RQA) problem. The general problem is NP-Hard in data-complexity, but we identify broad, tractable cases. We give a data-complexity map of the RQA problem over various classes of queries and constraints. In the intractable cases, we prove hardness. In the tractable cases, we provide query rewriting solutions.
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