research-article

Efficient Evaluation and Static Analysis for Well-Designed Pattern Trees with Projection

Authors:

Pablo Barceló,

Reinhard Pichler,

Sebastian SkritekAuthors Info & Claims

ACM Transactions on Database Systems (TODS), Volume 43, Issue 2

Article No.: 8, Pages 1 - 44

https://doi.org/10.1145/3233983

Published: 21 August 2018 Publication History

Abstract

Conjunctive queries (CQs) fail to provide an answer when the pattern described by the query does not exactly match the data. CQs might thus be too restrictive as a querying mechanism when data is semistructured or incomplete. The semantic web therefore provides a formalism—known as (projected) well-designed pattern trees (pWDPTs)—that tackles this problem: pWDPTs allow us to formulate queries that match parts of the query over the data if available, but do not ignore answers of the remaining query otherwise. Here we abstract away the specifics of semantic web applications and study pWDPTs over arbitrary relational schemas. Since the language of pWDPTs subsumes CQs, their evaluation problem is intractable. We identify structural properties of pWDPTs that lead to (fixed-parameter) tractability of various variants of the evaluation problem. We also show that checking if a pWDPT is equivalent to one in our tractable class is in 2EXPTIME. As a corollary, we obtain fixed-parameter tractability of evaluation for pWDPTs with such good behavior. Our techniques also allow us to develop a theory of approximations for pWDPTs.

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Cited By

Atre M(2022)The Case of SPARQL UNION, FILTER and DISTINCTProceedings of the ACM Web Conference 202210.1145/3485447.3511992(1882-1892)Online publication date: 25-Apr-2022
https://dl.acm.org/doi/10.1145/3485447.3511992
Angles RAranda CHogan ARojas CVrgoč D(2022)WDBench: A Wikidata Graph Query BenchmarkThe Semantic Web – ISWC 202210.1007/978-3-031-19433-7_41(714-731)Online publication date: 16-Oct-2022
https://doi.org/10.1007/978-3-031-19433-7_41
Mengel SSkritek S(2020)Characterizing Tractability of Simple Well-Designed Pattern Trees with ProjectionTheory of Computing Systems10.1007/s00224-020-10002-z65:1(3-41)Online publication date: 10-Sep-2020
https://dl.acm.org/doi/10.1007/s00224-020-10002-z
Show More Cited By

Index Terms

Efficient Evaluation and Static Analysis for Well-Designed Pattern Trees with Projection
1. Information systems
  1. Data management systems
    1. Query languages

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cover image ACM Transactions on Database Systems

ACM Transactions on Database Systems Volume 43, Issue 2

Best of ICDT 2017 and Regular Papers

June 2018

154 pages

ISSN:0362-5915

EISSN:1557-4644

DOI:10.1145/3243648

Editor:
Christian S. Jensen
Aalborg University, Denmark

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Copyright © 2018 ACM.

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Publication History

Published: 21 August 2018

Accepted: 01 June 2018

Revised: 01 April 2018

Received: 01 December 2016

Published in TODS Volume 43, Issue 2

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Cited By

Atre M(2022)The Case of SPARQL UNION, FILTER and DISTINCTProceedings of the ACM Web Conference 202210.1145/3485447.3511992(1882-1892)Online publication date: 25-Apr-2022
https://dl.acm.org/doi/10.1145/3485447.3511992
Angles RAranda CHogan ARojas CVrgoč D(2022)WDBench: A Wikidata Graph Query BenchmarkThe Semantic Web – ISWC 202210.1007/978-3-031-19433-7_41(714-731)Online publication date: 16-Oct-2022
https://doi.org/10.1007/978-3-031-19433-7_41
Mengel SSkritek S(2020)Characterizing Tractability of Simple Well-Designed Pattern Trees with ProjectionTheory of Computing Systems10.1007/s00224-020-10002-z65:1(3-41)Online publication date: 10-Sep-2020
https://dl.acm.org/doi/10.1007/s00224-020-10002-z
Bonifati AMartens WTimm T(2019)Navigating the Maze of Wikidata Query LogsThe World Wide Web Conference10.1145/3308558.3313472(127-138)Online publication date: 13-May-2019
https://dl.acm.org/doi/10.1145/3308558.3313472

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