To Form a More Perfect Union (Intersection, Difference)

Abstract

The AQUA [16] query algebra allows user-defined equivalence relations as arguments to query operators that generalize standard set operations. These predicates determine what objects are included in the query result, and the duplicates that must be removed.

While an expressive enhancement, the use of arbitrary equivalence relations to decide set membership can result in sets with counterintuitive behavior, and therefore can make queries return unreasonable results. In this paper, we show that equality predicates assume two roles with respect to sets. Distinguishers differentiate between set members and implicitly give meaning to standard set properties such as set equality. Constructors determine which object from input sets contribute to the query result. The requirements of distinguishers and constructors differ. AQUA’s set operators are problematic because they use constructors where distinguishers are required. We propose alternatives to AQUA’s set operators that address this limitation.

Contributors

Mitch Cherniack

Stanley B. Zdonik

Marian H. Nodine

Conference

Publication date: September 1995

Publication date (Print): September 1995

Pages: 1-12

Affiliations

Brown University

Providence, RI, USA

Article

DOI: 10.14236/ewic/DBPL1995.5

Copyright statement: © Mitch Cherniack et al. Published by BCS Learning and Development Ltd. Proceedings of the Fifth International Workshop on Database Programming Languages, Gubbio, Umbria, Italy

License:

This work is licensed under a Creative Commons Attribution 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

Conference name: Proceedings of the Fifth International Workshop on Database Programming Languages

Conference acronym: DBPL-5

Conference number: 5

Conference location: Gubbio, Umbria, Italy

Conference date: 6-8 September 1995

Conference sponsor: Electronic Workshops in Computing (eWiC)

Conference theme: Database Programming Languages

Product

Product Information: 1477-9358BCS Learning & Development

Self URI (article page): https://www.scienceopen.com/hosted-document?doi=10.14236/ewic/DBPL1995.5

Self URI (journal page): https://ewic.bcs.org/

Categories

Series title: Electronic Workshops in Computing