Uniform Operational Consistent Query Answering

Livshits, Ester; Pieris, Andréas; Schneider, Markus

doi:10.1145/3517804.3526230

Cited by 4 publications

(1 citation statement)

References 29 publications

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“…Calautti, Console, and Pieris present in [8] a complexity analysis of these counting problems under many-one logspace reductions and conducted an experimental evaluation of randomized approximation schemes for approximating the percentage of repairs that satisfy a given query [9]. CQA is also studied under different notions of repairs like operational repairs [10,12] and preferred repairs [48,29]. CQA has also been studied for queries with aggregation, in both theory and practice [16,28].…”

Section: Related Workmentioning

confidence: 99%

Consistent Query Answering for Primary Keys on Path Queries

Koutris

Ouyang

Wijsen

2021

Proceedings of the 40th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems

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We study the data complexity of consistent query answering (CQA) on databases that may violate the primary key constraints. A repair is a maximal subset of the database satisfying the primary key constraints. For a Boolean query q, the problem CERTAINTY(q) takes a database as input, and asks whether or not each repair satisfies q. The computational complexity of CERTAINTY(q) has been established whenever q is a selfjoin-free Boolean conjunctive query, or a (not necessarily self-join-free) Boolean path query. In this paper, we take one more step towards a general classification for all Boolean conjunctive queries by considering the class of rooted tree queries. In particular, we show that for every rooted tree query q, CERTAINTY(q) is in FO, NL-hard ∩ LFP, or coNP-complete, and it is decidable (in polynomial time), given q, which of the three cases applies. We also extend our classification to larger classes of queries with simple primary keys. Our classification criteria rely on query homomorphisms and our polynomial-time fixpoint algorithm is based on a novel use of context-free grammar (CFG).

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Section: Related Workmentioning

confidence: 99%

Consistent Query Answering for Primary Keys on Path Queries

Koutris

Ouyang

Wijsen

2021

Proceedings of the 40th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems

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Consistent Query Answering for Primary Keys on Rooted Tree Queries

Koutris,

Ouyang,

Wijsen

2024

Proc. ACM Manag. Data

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We study the data complexity of consistent query answering (CQA) on databases that may violate the primary key constraints. A repair is a maximal subset of the database satisfying the primary key constraints. For a Boolean query q, the problem fCERTAINTY(q) takes a database as input, and asks whether or not each repair satisfies q. The computational complexity of fCERTAINTY(q) has been established whenever q is a self-join-free Boolean conjunctive query, or a (not necessarily self-join-free) Boolean path query. In this paper, we take one more step towards a general classification for all Boolean conjunctive queries by considering the class of rooted tree queries. In particular, we show that for every rooted tree query q, fCERTAINTY(q) is in FO, NL-hard ∩ LPFL, or coNP-complete, and it is decidable (in polynomial time), given q, which of the three cases applies. We also extend our classification to larger classes of queries with simple primary keys. Our classification criteria rely on query homomorphisms and our polynomial-time fixpoint algorithm is based on a novel use of context-free grammar (CFG).

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Combined Approximations for Uniform Operational Consistent Query Answering

Calautti,

Livshits,

Pieris

et al. 2024

Proc. ACM Manag. Data

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Operational consistent query answering (CQA) is a recent framework for CQA based on revised definitions of repairs, which are built by applying a sequence of operations (e.g., fact deletions) starting from an inconsistent database until we reach a database that is consistent w.r.t. the given set of constraints. It has been recently shown that there is an efficient approximation for computing the percentage of repairs that entail a given query when we focus on primary keys, conjunctive queries, and assuming the query is fixed (i.e., in data complexity). However, it has been left open whether such an approximation exists when the query is part of the input (i.e., in combined complexity). We show that this is the case when we focus on self-join-free conjunctive queries of bounded generelized hypertreewidth. We also show that it is unlikely that efficient approximation schemes exist once we give up one of the adopted syntactic restrictions, i.e., self-join-freeness or bounding the generelized hypertreewidth. Towards the desired approximation, we introduce a counting complexity class, called SpanTL, show that each problem in it admits an efficient approximation scheme by using a recent approximability result about tree automata, and then place the problem of interest in SpanTL.

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Uniform Operational Consistent Query Answering

Cited by 4 publications

References 29 publications

Consistent Query Answering for Primary Keys on Path Queries

Consistent Query Answering for Primary Keys on Path Queries

Consistent Query Answering for Primary Keys on Rooted Tree Queries

Combined Approximations for Uniform Operational Consistent Query Answering

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