Consistent Query Answering for Primary Keys on Path Queries
Paraschos Koutris, Xiating Ouyang, Jef Wijsen

TL;DR
This paper analyzes the data complexity of consistent query answering for databases with primary key violations, revealing a four-way complexity classification for path queries when self-joins are permitted.
Contribution
It extends previous work by establishing a tetrachotomy classification for the complexity of CQA on path queries with self-joins, and provides a polynomial-time method to determine the complexity class.
Findings
Complexity of CERTAINTY(q) for path queries with self-joins falls into four classes.
Decidable in polynomial time which complexity class applies to a given query.
Provides a comprehensive classification extending known results for self-join-free queries.
Abstract
We study the data complexity of consistent query answering (CQA) on databases that may violate the primary key constraints. A repair is a maximal consistent subset of the database. For a Boolean query , the problem takes a database as input, and asks whether or not each repair satisfies . It is known that for any self-join-free Boolean conjunctive query , is in , -complete, or -complete. In particular, is in for any self-join-free Boolean path query . In this paper, we show that if self-joins are allowed, the complexity of for Boolean path queries exhibits a tetrachotomy between , -complete, -complete, and -complete. Moreover, it is decidable, in polynomial time…
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Taxonomy
TopicsCryptography and Data Security · Distributed systems and fault tolerance · Advanced Database Systems and Queries
