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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.

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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)

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@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.2023.23

Consistent Query Answering for Primary Keys and Conjunctive Queries with Counting

Authors: Aziz Amezian El Khalfioui and Jef Wijsen

Published in: LIPIcs, Volume 255, 26th International Conference on Database Theory (ICDT 2023)

Abstract

The problem of consistent query answering for primary keys and self-join-free conjunctive queries has been intensively studied in recent years and is by now well understood. In this paper, we study an extension of this problem with counting. The queries we consider count how many times each value occurs in a designated (possibly composite) column of an answer to a full conjunctive query. In a setting of database repairs, we adopt the semantics of [Arenas et al., ICDT 2001] which computes tight lower and upper bounds on these counts, where the bounds are taken over all repairs. Ariel Fuxman defined in his PhD thesis a syntactic class of queries, called Cforest, for which this computation can be done by executing two first-order queries (one for lower bounds, and one for upper bounds) followed by simple counting steps. We use the term "parsimonious counting" for this computation. A natural question is whether Cforest contains all self-join-free conjunctive queries that admit parsimonious counting. We answer this question negatively. We define a new syntactic class of queries, called Cparsimony, and prove that it contains all (and only) self-join-free conjunctive queries that admit parsimonious counting.

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Aziz Amezian El Khalfioui and Jef Wijsen. Consistent Query Answering for Primary Keys and Conjunctive Queries with Counting. In 26th International Conference on Database Theory (ICDT 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 255, pp. 23:1-23:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{amezianelkhalfioui_et_al:LIPIcs.ICDT.2023.23,
  author =	{Amezian El Khalfioui, Aziz and Wijsen, Jef},
  title =	{{Consistent Query Answering for Primary Keys and Conjunctive Queries with Counting}},
  booktitle =	{26th International Conference on Database Theory (ICDT 2023)},
  pages =	{23:1--23:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-270-9},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{255},
  editor =	{Geerts, Floris and Vandevoort, Brecht},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2023.23},
  URN =		{urn:nbn:de:0030-drops-177659},
  doi =		{10.4230/LIPIcs.ICDT.2023.23},
  annote =	{Keywords: Consistent query answering, primary key, conjunctive query, aggregation, counting}
}

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Documents authored by Amezian El Khalfioui, Aziz

Computing Consistent Least Upper Bounds in Aggregate Logic

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Consistent Query Answering for Primary Keys and Conjunctive Queries with Counting

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