Decomposition-Based Consistent Query Answering in Databases with Universal Constraints under Cardinality-Based Semantics

Consistent query answering (CQA) in relational databases under cardinality-based semantics is a well-known approach to dealing with inconsistency between databases and certain integrity constraints (ICs). It computes from a given database all consistent answers to a query that are satisfied by all the C-repairs, where a C-repair is a database that satisfies all the given ICs and minimizes the cardinality of the set of tuples in the symmetric difference with the given database. In this paper we address the problem of CQA in databases with universal constraints under cardinality-based semantics. This problem has no worst-case optimal solutions by now. We present a novel method for such problem which is worst-case optimal in terms of time data complexity and is further optimized by a decomposition-based framework. Experimental results on synthetic databases demonstrate the advantages of the proposed method.