CAvSAT: Answering Aggregation Queries over Inconsistent Databases via SAT Solving

Abstract

Consistent Query Answering (CQA) is a rigorous and principled approach to answering queries posed against inconsistent databases. Computing consistent answers to a Select-Project-Join (SPJ) query or an SPJ query with aggregation operators on a given inconsistent database can be an intractable problem. We demonstrate CAvSAT, a system for CQA that leverages a set of natural reductions from a given CQA instance to boolean Satisfiability (SAT) and its optimization variants. CAvSAT is the first system that is capable of handling unions of SPJ queries with aggregation operators SUM and COUNT, and databases that are inconsistent w.r.t. key constraints, functional dependencies, and denial constraints.