55 Search Results for "Cate, Balder ten"

Volume

LIPIcs, Volume 365

29th International Conference on Database Theory (ICDT 2026)

ICDT 2026, Tampere, Finland, March 24-27, 2026

Editors: Balder ten Cate and Maurice Funk

Document
Complete Volume
DOI: 10.4230/LIPIcs.ICDT.2026
LIPIcs, Volume 365, ICDT 2026, Complete Volume

Authors: Balder ten Cate and Maurice Funk

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
LIPIcs, Volume 365, ICDT 2026, Complete Volume
Cite as

29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 1-486, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@Proceedings{tencate_et_al:LIPIcs.ICDT.2026,
  title =	{{LIPIcs, Volume 365, ICDT 2026, Complete Volume}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{1--486},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026},
  URN =		{urn:nbn:de:0030-drops-256660},
  doi =		{10.4230/LIPIcs.ICDT.2026},
  annote =	{Keywords: LIPIcs, Volume 365, ICDT 2026, Complete Volume}
}
Document
Front Matter
DOI: 10.4230/LIPIcs.ICDT.2026.0
Front Matter, Table of Contents, Preface, Conference Organization

Authors: Balder ten Cate and Maurice Funk

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
Front Matter, Table of Contents, Preface, Conference Organization
Cite as

29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 0:i-0:xvi, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{tencate_et_al:LIPIcs.ICDT.2026.0,
  author =	{ten Cate, Balder and Funk, Maurice},
  title =	{{Front Matter, Table of Contents, Preface, Conference Organization}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{0:i--0:xvi},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.0},
  URN =		{urn:nbn:de:0030-drops-256655},
  doi =		{10.4230/LIPIcs.ICDT.2026.0},
  annote =	{Keywords: Front Matter, Table of Contents, Preface, Conference Organization}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2026.1
Query Decompositions and All That (Invited Talk)

Authors: Kyle Deeds, Timo Camillo Merkl, Reinhard Pichler, and Dan Suciu

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
The close relationship between Conjunctive Queries (CQs) and Constraint Satisfaction Problems (CSPs) has long been known. Nevertheless, apart from decomposition methods, research on efficient query evaluation or constraint solving algorithms has developed rather independently. In this article, we illustrate how search algorithms originating from the CSP community can be fruitfully applied to query evaluation - either by further developing the original search algorithms or by combining them with query decomposition methods. It turns out that the resulting approaches may indeed lead to lower time and/or space complexity than previous query evaluation methods.
Cite as

Kyle Deeds, Timo Camillo Merkl, Reinhard Pichler, and Dan Suciu. Query Decompositions and All That (Invited Talk). In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 1:1-1:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{deeds_et_al:LIPIcs.ICDT.2026.1,
  author =	{Deeds, Kyle and Merkl, Timo Camillo and Pichler, Reinhard and Suciu, Dan},
  title =	{{Query Decompositions and All That}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{1:1--1:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.1},
  URN =		{urn:nbn:de:0030-drops-256158},
  doi =		{10.4230/LIPIcs.ICDT.2026.1},
  annote =	{Keywords: Query evaluation, Query decompositions, Complexity}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2026.2
The Dissection of a Complex Event Recognition Engine (Invited Talk)

Authors: Cristian Riveros

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
Complex Event Recognition (CER) is a group of data management technologies that model data streams as sequences of events, where users are interested in recognizing complex events, namely, groups of events that represent critical situations in real life. Examples of complex events could include a fire detected by a sensor network in a nature reserve, an accident recognized by cameras in a smart city, or a critical social event in a social network. In these scenarios, event streams are generated continuously at high speed, and the importance of each event decays rapidly over time. To process them, a complex event recognition engine is a data management software that must efficiently process such data and alert on the presence of complex events in real time. In this talk, we will present the dissection of CORE [Kyle Bossonney et al., 2025; Marco Bucchi et al., 2022], a novel complex event recognition engine. The dissection will cover all its internal components: starting with its architecture, we will examine its query language, stream and memory management, query optimization, query evaluation, and complex event outputting. We will focus on the technical solutions and challenges of a CER engine, from both theoretical [Alejandro Grez et al., 2019; Alejandro Grez et al., 2021] and practical [Kyle Bossonney et al., 2025; Marco Bucchi et al., 2022] perspectives. In particular, based on our understanding of its components, we will review several open research problems and possible directions for future work in complex event recognition.
Cite as

Cristian Riveros. The Dissection of a Complex Event Recognition Engine (Invited Talk). In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, p. 2:1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{riveros:LIPIcs.ICDT.2026.2,
  author =	{Riveros, Cristian},
  title =	{{The Dissection of a Complex Event Recognition Engine}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{2:1--2:1},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.2},
  URN =		{urn:nbn:de:0030-drops-256169},
  doi =		{10.4230/LIPIcs.ICDT.2026.2},
  annote =	{Keywords: Streams, complex event recognition, query evaluation, query optimization}
}
Document
Invited Talk
DOI: 10.4230/LIPIcs.ICDT.2026.3
Building Relational Circuits (Invited Talk)

Authors: Florent Capelli

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
We review two algorithms which allow to build a factorized representation of the answers set of join queries. In a nutshell, the representation builds a circuit representing the answers set of a join query by starting from atomic relations and iteratively combine them by either constructing the Cartesian product or the disjoint union of previously computed relations. The first one can be seen as the trace of the celebrated Yannakakis algorithm, building the answer set from the inputs to the output of the circuit while the second adopts a top-down approach which can be seen as a generalization of the exhaustive DPLL algorithm, originally designed to solve the #SAT problem.
Cite as

Florent Capelli. Building Relational Circuits (Invited Talk). In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 3:1-3:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{capelli:LIPIcs.ICDT.2026.3,
  author =	{Capelli, Florent},
  title =	{{Building Relational Circuits}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{3:1--3:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.3},
  URN =		{urn:nbn:de:0030-drops-256172},
  doi =		{10.4230/LIPIcs.ICDT.2026.3},
  annote =	{Keywords: Conjunctive queries, factorized databases, knowledge compilation}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.4
Computing Consistent Least Upper Bounds in Aggregate Logic

Authors: Aziz Amezian El Khalfioui and Jef Wijsen

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
We consider the problem of answering conjunctive queries with aggregation on database instances that may violate primary key constraints. In SQL, these queries follow the SELECT-FROM-WHERE-GROUP BY format, where the WHERE clause involves a conjunction of equalities, and the SELECT clause can incorporate aggregate operators like MAX, MIN, SUM, AVG, or COUNT. Repairs of a database instance are defined as inclusion-maximal subsets that satisfy all primary keys. The range-consistent answer to a numerical query over an inconsistent database is a pair [glb, lub], where glb and lub are, respectively, the smallest and the greatest results returned by the query over all possible repairs. While previous work has focused on the computation of the glb, the current paper studies the computation of the lub for a numerical domain of non-negative rational numbers. We introduce the notion of κ-acyclicity for self-join-free conjunctive queries. We show that if the body of a SUM-query is κ-acyclic, then the lub can be computed through a rewriting in first-order aggregate logic. Moreover, we show that this result extends to all aggregate operators that are monotone and associative. Importantly, we also prove the inverse: if the body of a SUM-query is not κ-acyclic, then the lub cannot be computed in first-order aggregate logic.
Cite as

Aziz Amezian El Khalfioui and Jef Wijsen. Computing Consistent Least Upper Bounds in Aggregate Logic. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 4:1-4:21, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{amezianelkhalfioui_et_al:LIPIcs.ICDT.2026.4,
  author =	{Amezian El Khalfioui, Aziz and Wijsen, Jef},
  title =	{{Computing Consistent Least Upper Bounds in Aggregate Logic}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{4:1--4:21},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.4},
  URN =		{urn:nbn:de:0030-drops-256180},
  doi =		{10.4230/LIPIcs.ICDT.2026.4},
  annote =	{Keywords: Consistent query answering, primary key, conjunctive query, aggregate logic}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.5
Rule Rewriting Revisited: A Fresh Look at Static Filtering for Datalog and ASP

Authors: Philipp Hanisch and Markus Krötzsch

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
Static filtering is a data-independent optimisation method for Datalog, which generalises algebraic query rewriting techniques from relational databases. In spite of its early discovery by Kifer and Lozinskii in 1986, the method has been overlooked in recent research and system development, and special cases are being rediscovered independently. We therefore recall the original approach, using updated terminology and more general filter predicates that capture features of modern systems, and we show how to extend its applicability to answer set programming (ASP). The outcome is strictly more general but also more complex than the classical approach: double exponential in general and single exponential even for predicates of bounded arity. As a solution, we propose tractable approximations of the algorithm that can still yield much improved logic programs in typical cases, e.g., it can improve the performance of rule systems over real-world data in the order of magnitude.
Cite as

Philipp Hanisch and Markus Krötzsch. Rule Rewriting Revisited: A Fresh Look at Static Filtering for Datalog and ASP. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 5:1-5:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{hanisch_et_al:LIPIcs.ICDT.2026.5,
  author =	{Hanisch, Philipp and Kr\"{o}tzsch, Markus},
  title =	{{Rule Rewriting Revisited: A Fresh Look at Static Filtering for Datalog and ASP}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{5:1--5:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.5},
  URN =		{urn:nbn:de:0030-drops-256197},
  doi =		{10.4230/LIPIcs.ICDT.2026.5},
  annote =	{Keywords: Rule rewriting, static optimisation, static filtering, Datalog, Answer Set Programming}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.6
Designing and Comparing RPQ Semantics

Authors: Victor Marsault and Antoine Meyer

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
Modern Property graph database query languages such as Cypher, PGQL, GSQL, and the standard GQL draw inspiration from the formalism of regular path queries (RPQs). In order to output walks explicitly, they depart from the classical and well-studied homomorphism semantics. However, it then becomes difficult to present results to users because RPQs may match infinitely many walks. The aforementioned languages use ad-hoc criteria to select a finite subset of those matches. For instance, Cypher uses trail semantics, discarding walks with repeated edges; PGQL and GSQL use shortest walk semantics, retaining only the walks of minimal length among all matched walks; and GQL allows users to choose from several semantics. Even though there is academic research on these semantics, it focuses almost exclusively on evaluation efficiency. In an attempt to better understand, choose and design RPQ semantics, we present a framework to categorize and compare them according to other criteria. We formalize several possible properties, pertaining to the study of RPQ semantics seen as mathematical functions mapping a database and a query to a finite set of walks. We show that some properties are mutually exclusive, or cannot be met. We also give several new RPQ semantics as examples. Some of them may provide ideas for the design of new semantics for future graph database query languages.
Cite as

Victor Marsault and Antoine Meyer. Designing and Comparing RPQ Semantics. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 6:1-6:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{marsault_et_al:LIPIcs.ICDT.2026.6,
  author =	{Marsault, Victor and Meyer, Antoine},
  title =	{{Designing and Comparing RPQ Semantics}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{6:1--6:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.6},
  URN =		{urn:nbn:de:0030-drops-256200},
  doi =		{10.4230/LIPIcs.ICDT.2026.6},
  annote =	{Keywords: Regular Path Queries, RPQ, Semantics, Graph Databases, Pattern matching, Regular Expression}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.7
The Importance of Parameters in Ranking Functions

Authors: Christoph Standke, Nikolaos Tziavelis, Wolfgang Gatterbauer, and Benny Kimelfeld

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
How important is the weight of a given column in determining the ranking of tuples in a table? To address such an explanation question about a ranking function, we investigate the computation of SHAP scores for column weights, adopting a recent framework by Grohe et al. [ICDT'24]. The exact definition of this score depends on three key components: (1) the ranking function in use, (2) an effect function that quantifies the impact of using alternative weights on the ranking, and (3) an underlying weight distribution. We analyze the computational complexity of different instantiations of this framework for a range of fundamental ranking and effect functions, focusing on probabilistically independent finite distributions for individual columns. For the ranking functions, we examine lexicographic orders and score-based orders defined by the summation, minimum, and maximum functions. For the effect functions, we consider global, top-k, and local perspectives: global measures quantify the divergence between the perturbed and original rankings, top-k measures inspect the change in the set of top-k answers, and local measures capture the impact on an individual tuple of interest. Although all cases admit an additive fully polynomial-time randomized approximation scheme (FPRAS), we establish the complexity of exact computation, identifying which cases are solvable in polynomial time and which are #P-hard. We further show that all complexity results, lower bounds and upper bounds, extend to a related task of computing the Shapley value of whole columns (regardless of their weight).
Cite as

Christoph Standke, Nikolaos Tziavelis, Wolfgang Gatterbauer, and Benny Kimelfeld. The Importance of Parameters in Ranking Functions. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 7:1-7:18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{standke_et_al:LIPIcs.ICDT.2026.7,
  author =	{Standke, Christoph and Tziavelis, Nikolaos and Gatterbauer, Wolfgang and Kimelfeld, Benny},
  title =	{{The Importance of Parameters in Ranking Functions}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{7:1--7:18},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.7},
  URN =		{urn:nbn:de:0030-drops-256217},
  doi =		{10.4230/LIPIcs.ICDT.2026.7},
  annote =	{Keywords: Ranking, Explanation, Shapley value, SHAP scores}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.8
Neither Cover nor Pack: Distributed Worst-Case Optimality of Degree-2 Joins

Authors: Heba Aamer, Xiao Hu, and Bas Ketsman

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
We study the worst-case communication complexity of the join query evaluation problem over large-scale data in distributed shared-nothing systems under the MPC model. We focus on multi-round MPC algorithms that run in constant number of rounds. The problem is well-understood for a few classes of queries, mainly the class of acyclic queries and the class of graph-like queries. For queries not belonging to either class, the complexity picture is much less clear. We study the class of degree-two queries and fragments thereof. In this paper, we tighten the gap between the upper and lower bounds for the studied classes and establish worst-case optimality for some fragments of the considered classes. We also debunk a well-believed conjecture about which query-related quantity, in the worst-case, optimally captures the communication complexity of the studied problem.
Cite as

Heba Aamer, Xiao Hu, and Bas Ketsman. Neither Cover nor Pack: Distributed Worst-Case Optimality of Degree-2 Joins. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 8:1-8:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{aamer_et_al:LIPIcs.ICDT.2026.8,
  author =	{Aamer, Heba and Hu, Xiao and Ketsman, Bas},
  title =	{{Neither Cover nor Pack: Distributed Worst-Case Optimality of Degree-2 Joins}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{8:1--8:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.8},
  URN =		{urn:nbn:de:0030-drops-256226},
  doi =		{10.4230/LIPIcs.ICDT.2026.8},
  annote =	{Keywords: degree-two joins, worst-case optimality, distributed algorithms}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.9
Acyclic Join Sampling Under Selections: Dichotomy, Union Sampling, and Enumeration

Authors: Jinchao Huang, Yufei Tao, and Sibo Wang

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
Previous research on join sampling has focused on joins without selection conditions, even though such conditions are prevalent in everyday queries in database systems. Motivated by this, we undertake a systematic investigation on the complexity of sampling from the result of an acyclic join under equality conditions given only at runtime. When conditions are conjunctive, the goal is to understand when it is possible to precompute a feasible structure that uses Õ(IN) space and supports sampling in Õ(1) time, where IN is the input size. We present a dichotomy to characterize (subject to a widely-accepted conjecture) the existence of such structures based on the conditions supplied and, in every feasible scenario, give an optimal structure of O(IN) space and O(1) sample time. We then extend our investigation to conditions expressed in disjunctive normal form, where the core challenge reduces to the fundamental set union sampling problem. We overcome the challenge with an optimal algorithm and utilize it to develop optimal sampling structures. Our findings also lead to new results on the closely-related random enumeration problem.
Cite as

Jinchao Huang, Yufei Tao, and Sibo Wang. Acyclic Join Sampling Under Selections: Dichotomy, Union Sampling, and Enumeration. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 9:1-9:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{huang_et_al:LIPIcs.ICDT.2026.9,
  author =	{Huang, Jinchao and Tao, Yufei and Wang, Sibo},
  title =	{{Acyclic Join Sampling Under Selections: Dichotomy, Union Sampling, and Enumeration}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{9:1--9:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.9},
  URN =		{urn:nbn:de:0030-drops-256231},
  doi =		{10.4230/LIPIcs.ICDT.2026.9},
  annote =	{Keywords: Conjunctive Queries, Acyclic Joins, Sampling, Lower Bounds}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.10
Bounding the Makespan of Transaction Schedules

Authors: Tim Baccaert, Brecht Vandevoort, and Bas Ketsman

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
The performance of transactional database systems is typically evaluated by measuring the amount of transactions they can commit to the database per second. However, fairly measuring this for the same workload on different systems is not trivial. It is therefore relevant to formalize schedule efficiency, investigate the space of all possible efficient schedules, and identify whether there is any room for improvement. Prior transaction theory largely centers on decision problems relating to safety, such as the serializability, robustness, and allocation problems. Most pertinently, these problems take already scheduled transactions as input, and do not directly consider the efficiency of those schedules. In this work, we define schedules as assignments of operations on objects to discrete points in time. This allows us to quantify efficiency as the elapsed duration between the schedule’s beginning and end, more commonly known as the makespan in the scheduling literature. We establish that, given some set of transactions and a desired makespan, it is NP-complete to decide if there exists a conflict serializable schedule which is bounded by that makespan. We additionally provide an instance optimal algorithm for scheduling transaction sets with a single contention point, that is, exactly one object may appear in conflicting operations. Lastly, we give worst-case optimal bounds on the makespan, meaning that schedules can never exceed this bound, and for the worst transaction sets, the bound is optimal.
Cite as

Tim Baccaert, Brecht Vandevoort, and Bas Ketsman. Bounding the Makespan of Transaction Schedules. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 10:1-10:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{baccaert_et_al:LIPIcs.ICDT.2026.10,
  author =	{Baccaert, Tim and Vandevoort, Brecht and Ketsman, Bas},
  title =	{{Bounding the Makespan of Transaction Schedules}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{10:1--10:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.10},
  URN =		{urn:nbn:de:0030-drops-256242},
  doi =		{10.4230/LIPIcs.ICDT.2026.10},
  annote =	{Keywords: Transactions, Scheduling, Discrete Optimization, Complexity}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.11
Factorised Representations of Join Queries: Tight Bounds and a New Dichotomy

Authors: Christoph Berkholz and Harry Vinall-Smeeth

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
A common theme in factorised databases and knowledge compilation is the representation of solution sets in a useful yet succinct data structure. In this paper, we study the representation of the result of join queries (or, equivalently, the set of homomorphisms between two relational structures). We focus on the very general format of {∪,×}-circuits - also known as d-representations or DNNF circuits - and aim to find the limits of this approach. In prior work, it has been shown that there always exists a {∪,×}-circuit of size N^O(subw) representing the query result, where N is the size of the database and subw the submodular width of the query. If the arity of all relations is bounded by a constant, then subw is linear in the treewidth tw of the query. In this setting, the authors of this paper proved a lower bound of N^Ω(tw^ε) on the circuit size (ICALP 2023), where ε > 0 depends on the excluded grid theorem. Our first main contribution is to improve this lower bound to N^Ω(tw), which is tight up to a constant factor in the exponent. Our second contribution is a N^Ω(subw^{1/4}) lower bound on the circuit size for join queries over relations of unbounded arity. Both lower bounds are unconditional lower bounds on the circuit size for well-chosen database instances. Their proofs use a combination of structural (hyper)graph theory with communication complexity in a simple yet novel way. While the second lower bound is asymptotically equivalent to Marx’s conditional bound on the decision complexity (JACM 2013), our N^Θ(tw) bound in the bounded arity setting is tight, while the best conditional bound on the decision complexity is N^Ω(tw/log tw). Note that removing this logarithmic factor in the decision setting is a major open problem.
Cite as

Christoph Berkholz and Harry Vinall-Smeeth. Factorised Representations of Join Queries: Tight Bounds and a New Dichotomy. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 11:1-11:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{berkholz_et_al:LIPIcs.ICDT.2026.11,
  author =	{Berkholz, Christoph and Vinall-Smeeth, Harry},
  title =	{{Factorised Representations of Join Queries: Tight Bounds and a New Dichotomy}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{11:1--11:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.11},
  URN =		{urn:nbn:de:0030-drops-256255},
  doi =		{10.4230/LIPIcs.ICDT.2026.11},
  annote =	{Keywords: join queries, homomorphisms, factorised databases, succinct representation, knowledge compilation, lower bounds}
}
Document
DOI: 10.4230/LIPIcs.ICDT.2026.12
The Complexity of Finding Missing Answer Repairs

Authors: Jesse Comer and Val Tannen

Published in: LIPIcs, Volume 365, 29th International Conference on Database Theory (ICDT 2026)

Abstract
We investigate the problem of identifying database repairs for missing tuples in query answers. We show that when the query is part of the input - the combined complexity setting - determining whether or not a repair exists is polynomial-time equivalent to the satisfiability problem for classes of queries admitting a weak form of projection and selection. We then identify the sub-classes of unions of conjunctive queries with negated atoms, defined by the relational algebra operations permitted to appear in the query, for which the minimal repair problem can be solved in polynomial time. In contrast, we show that the problem is NP-hard, as well as set cover-hard to approximate via strict reductions, whenever both projection and join are permitted in the input query. Additionally, we show that finding the size of a minimal repair for unions of conjunctive queries (with negated atoms permitted) is OptP[log(n)]-complete, while computing a minimal repair is possible with O(n²) queries to an NP oracle. With recursion permitted, the combined complexity of all of these variants increases significantly, with an EXP lower bound. However, from the data complexity perspective, we show that minimal repairs can be identified in polynomial time for all queries expressible as semi-positive datalog programs.
Cite as

Jesse Comer and Val Tannen. The Complexity of Finding Missing Answer Repairs. In 29th International Conference on Database Theory (ICDT 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 365, pp. 12:1-12:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

Copy BibTex To Clipboard

@InProceedings{comer_et_al:LIPIcs.ICDT.2026.12,
  author =	{Comer, Jesse and Tannen, Val},
  title =	{{The Complexity of Finding Missing Answer Repairs}},
  booktitle =	{29th International Conference on Database Theory (ICDT 2026)},
  pages =	{12:1--12:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-413-0},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{365},
  editor =	{ten Cate, Balder and Funk, Maurice},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2026.12},
  URN =		{urn:nbn:de:0030-drops-256265},
  doi =		{10.4230/LIPIcs.ICDT.2026.12},
  annote =	{Keywords: Missing answers, database repairs, datalog, computational complexity}
}
  • Refine by Type
  • 54 Document/PDF
  • 14 Document/HTML
  • 1 Volume

  • Refine by Publication Year
  • 32 2026
  • 12 2025
  • 4 2024
  • 1 2021
  • 1 2019
  • Show More...

  • Refine by Author
  • 11 ten Cate, Balder
  • 5 Kolaitis, Phokion G.
  • 3 Dalmau, Victor
  • 3 Kimelfeld, Benny
  • 3 Peterfreund, Liat
  • Show More...

  • Refine by Series/Journal
  • 49 LIPIcs
  • 3 OASIcs
  • 1 TGDK
  • 1 DagRep

  • Refine by Classification
  • 13 Theory of computation → Database theory
  • 9 Theory of computation → Logic and databases
  • 8 Theory of computation → Logic
  • 7 Information systems → Query languages
  • 6 Information systems → Graph-based database models
  • Show More...

  • Refine by Keyword
  • 5 Conjunctive Queries
  • 5 Datalog
  • 3 Data Examples
  • 2 Complexity
  • 2 Craig Interpolation
  • Show More...

Any Issues?
X

Feedback on the Current Page

CAPTCHA

Thanks for your feedback!

Feedback submitted to Dagstuhl Publishing

Could not send message

Please try again later or send an E-mail
© 2023-2026 Schloss Dagstuhl – LZI GmbH Schloss Dagstuhl – LZI GmbH About DROPS Imprint Privacy Contact