Repairing and Querying Inconsistent Databases

Abstract

The integration of knowledge from multiple sources is an important aspect in several areas such as data warehousing, database integration, automated reasoning systems, active reactive databases and others. Thus a central topic in databases is the construction of integration systems, designed for retrieving and querying uniform data stored in multiple information sources. This chapter illustrates recent techniques for computing repairs as well as consistent answers over inconsistent databases. Often databases may be inconsistent with respect to a set of integrity constraints, that is, one or more integrity constraints are not satisfied. Most of the techniques for computing repairs and queries over inconsistent databases work for restricted cases and only recently there have been proposals to consider more general constraints. In this chapter we give an informal description of the main techniques proposed in the literature.