Fixing Numerical Attributes Under Integrity Constraints
Leopoldo Bertossi, Loreto Bravo, Enrico Franconi, Andrei Lopatenko · 2005
Consistent query answering is the problem of computing the answers from a database that are consistent with respect to certain integrity constraints that the database as whole may fail to satisfy. Those answers are characterized as invariant under minimal forms of restoring the consistency of the database. In this context, we study the problem of repairing databases by fixing numerical data at the attribute level. For their relevance in database applications with numerical domains, we consider denial and aggregate constraints. After providing a quantitative definition of database fix, we investigate the computational complexity of different problems, such as the existence and verification of fixes, and deciding consistency of answers to conjunctive aggregate queries. We show tractability for special cases; and provide approximation algorithms for some of the hard cases. 1