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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/11849

Title: Relational completeness of query languages for annotated databases
Authors: Geerts, Floris
VAN DEN BUSSCHE, Jan
Issue Date: 2011
Publisher: ACADEMIC PRESS INC ELSEVIER SCIENCE
Citation: JOURNAL OF COMPUTER AND SYSTEM SCIENCES, 77(3). p. 491-504
Abstract: Annotated relational databases can be queried either by simply making the annotations explicitly available along the ordinary data, or by adapting the standard query operators so that they have an implicit effect also on the annotations. We compare the expressive power of these two approaches. As a formal model for the implicit approach we propose the color algebra, an adaptation of the relational algebra to deal with the annotations. We show that the color algebra is relationally complete: it is equivalent to the relational algebra on the explicit annotations. Our result extends a similar completeness result established for the query algebra of the MONDRIAN annotation system, from unions of conjunctive queries to the full relational algebra. We also show that the color algebra is nonredundant: no operator can be expressed in terms of the other operators. We also present a generalization of the color algebra that is relationally complete in the presence of built-in predicates on the annotations. (C) 2010 Elsevier Inc. All rights reserved.
Notes: [Geerts, Floris] Univ Edinburgh, Edinburgh EH8 9YL, Midlothian, Scotland. [Van den Bussche, Jan] Transnct Univ Limburg, Hasselt Univ, Hasselt, Belgium.
URI: http://hdl.handle.net/1942/11849
DOI: 10.1016/j.jcss.2010.04.007
ISI #: 000288474800004
ISSN: 0022-0000
Category: A1
Type: Journal Contribution
Validation: ecoom, 2012
Appears in Collections: Research publications

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