A logic-based framework for database repairs

TL;DR

This paper presents a comprehensive logic-based framework for database repairs that unifies various existing notions, models constraints and query relations, and analyzes the complexity of repair-related problems.

Contribution

It introduces a general abstract framework for database repairs using formal logic, unifies different repair notions, and extends to semiring annotated databases with complexity analysis.

Findings

Framework unifies set-based and cardinality-based repairs.

Models both integrity and query constraints distinctly.

Provides complexity results for repair existence and query answering.

Abstract

We introduce a general abstract framework for database repairs, where the repair notions are defined using formal logic. We distinguish between integrity constraints and so-called query constraints. The former are used to model consistency and desirable properties of the data (such as functional dependencies and independencies), while the latter relate two database instances according to their answers to the query constraints. The framework allows for a distinction between hard and soft queries, allowing the answers to a core set of queries to be preserved, as well as defining a distance between instances based on query answers. We illustrate how different notions of repairs from the literature can be modelled within our unifying framework. The framework generalises both set-based and cardinality based repairs to semiring annotated databases. Furthermore, we initiate a complexity-theoretic analysis of consistent query answering and checking existence of a repair within the framework.