Conditional functional dependencies for capturing data inconsistencies

作者：Wenfei Fan, Floris Geerts, Xibei Jia, Anastasios Kementsietsidis · 发表于：ACM Transactions on Database Systems · 年份：2008 · DOI：10.1145/1366102.1366103 · 被引用次数：463 · 研究领域：Data Quality and Management、Semantic Web and Ontologies、Advanced Database Systems and Queries

We propose a class of integrity constraints for relational databases, referred to as conditional functional dependencies (CFDs), and study their applications in data cleaning. In contrast to traditional functional dependencies (FDs) that were developed mainly for schema design, CFDs aim at capturing the consistency of data by enforcing bindings of semantically related values. For static analysis of CFDs we investigate the consistency problem , which is to determine whether or not there exists a nonempty database satisfying a given set of CFDs, and the implication problem , which is to decide whether or not a set of CFDs entails another CFD. We show that while any set of transitional FDs is trivially consistent, the consistency problem is NP-complete for CFDs, but it is in PTIME when either the database schema is predefined or no attributes involved in the CFDs have a finite domain. For the implication analysis of CFDs, we provide an inference system analogous to Armstrong's axioms for FDs, and show that the implication problem is coNP-complete for CFDs in contrast to the linear-time complexity for their traditional counterpart. We also present an algorithm for computing a minimal cover of a set of CFDs. Since CFDs allow data bindings, in some cases CFDs may be physically large, complicating the detection of constraint violations. We develop techniques for detecting CFD violations in SQL as well as novel techniques for checking multiple constraints by a single query. We also p...