Consistent Query Answering for Primary Keys and Conjunctive Queries with Counting
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| Title: | Consistent Query Answering for Primary Keys and Conjunctive Queries with Counting |
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| Authors: | Amezian El Khalfioui, Aziz, Wijsen, Jef |
| Contributors: | Aziz Amezian El Khalfioui and Jef Wijsen |
| Publication Status: | Preprint |
| Publisher Information: | arXiv, 2022. |
| Publication Year: | 2022 |
| Subject Terms: | primary key, FOS: Computer and information sciences, Consistent query answering, conjunctive query, Computer Science - Databases, aggregation, 0202 electrical engineering, electronic engineering, information engineering, counting, Databases (cs.DB), 02 engineering and technology, ddc:004, 3. Good health |
| Description: | 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 C_forest, 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 C_forest 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 C_parsimony, and prove that it contains all (and only) self-join-free conjunctive queries that admit parsimonious counting. 27 pages, 2 figures |
| Document Type: | Article Conference object |
| File Description: | application/pdf |
| DOI: | 10.48550/arxiv.2211.04134 |
| DOI: | 10.4230/lipics.icdt.2023.23 |
| Access URL: | http://arxiv.org/abs/2211.04134 https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ICDT.2023.23 |
| Rights: | CC BY |
| Accession Number: | edsair.doi.dedup.....8da52fb34c765d0af87e09ebbda62695 |
| Database: | OpenAIRE |
Nájsť tento článok vo Web of Science | 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 C_forest, 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 C_forest 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 C_parsimony, and prove that it contains all (and only) self-join-free conjunctive queries that admit parsimonious counting.<br />27 pages, 2 figures |
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| DOI: | 10.48550/arxiv.2211.04134 |