Checking Consistency of Database Constraints

This paper addresses the problem of consistency of a set of integrity constraints itself, independent from any state. It is pointed out that database constraints have not only to be consistent, but in addition to be finitely satisfiable. This stronger property reflects that the constraints have to admit a finite set of (stored as well as derivable) facts. As opposed to consistency, being undecidable, finite satisfiability is semidecidable. For efficiency purposes we investigate methods that check both finite satisfiability as well as unsatisfiability . Two different methods are proposed which extend two alternative approaches to refutation

Implementing version support for complex objects

New applications in the area of office information systems, computer aided design and manufacturing make new demands upon database management systems. Among others highly structured objects and their history have to be represented and manipulated. The paper discusses some general problems concerning the access and storage of complex objects with their versions and the solutions developed within the AIM/II project. Queries related to versions are distinguished in ASOF queries (asking information valid at a certain moment) and WALK-THROUGH-TIME (WTT) queries (obtaining trend information concerning a certain period). In the paper some new algorithms to handle such queries are presented. A brief analysis gives an indication about the performance of query processing in historical databases

Modeling controlled vocabularies using OODBs and multilevel area diagrams

A Controlled Vocabulary (CV) is a software system of domain knowledge that consolidates and unifies the terminology of a large application domain. With a common, centralized CV, costly and time-consuming translations can be eliminated between pairs of organizations and pairs of software systems. Unfortunately, the more knowledge we put into a CV, the harder it is to understand and maintain it. In this dissertation, a comprehensive theoretical methodology for modeling CVs using Object-Oriented Database (OODB) technology is presented. We present two methods for representing a semantic network CV as an equivalent OODB, which we call an Object-Oriented Vocabulary Repository (OOVR). The first method, based on a structural analysis and partitioning of the CV, yields an OODB with a very concise schema, referred to as the OOVR schema. Due to its compact size, the schema can be displayed on one or a few computer screens and serves as an aid for comprehending and maintaining the CV. A program called the Object-Oriented Vocabulary Repository Generator (OOVR Generator) has been built to automatically generate an OOVR for a given semantic network CV. Our second methodology results in a larger schema, which, however, serves as an important tool for browsing and navigation through a CV. The OODB schemas created by both methodologies provide important abstract views of CVs. We have also defined a new type of semantic relationships called IS-A\u27 in the context of an OOVR representation. The IS-A\u27 relationships are defined on OOVR schemas to reflect certain important IS-A relationships in the underlying CV. The two OOVR representations exhibit several interesting theoretical characteristics which are formally proven in this dissertation. To provide an environment with several abstract views of a CV, we also define a paradigm called Multilevel Area Diagrams (MLADs). A MLAD is a collection of different partitions of increasing detail and decreasing abstraction derived from a CV. Users can browse at one level and then switch to another level to continue their navigation. Examples of browsing sessions are presented to show that the MLAD paradigm provides processing capabilities beyond those of a traditional object-oriented representation of a vocabulary

Workshop on Database Programming Languages

These are the revised proceedings of the Workshop on Database Programming Languages held at Roscoff, Finistère, France in September of 1987. The last few years have seen an enormous activity in the development of new programming languages and new programming environments for databases. The purpose of the workshop was to bring together researchers from both databases and programming languages to discuss recent developments in the two areas in the hope of overcoming some of the obstacles that appear to prevent the construction of a uniform database programming environment. The workshop, which follows a previous workshop held in Appin, Scotland in 1985, was extremely successful. The organizers were delighted with both the quality and volume of the submissions for this meeting, and it was regrettable that more papers could not be accepted. Both the stimulating discussions and the excellent food and scenery of the Brittany coast made the meeting thoroughly enjoyable. There were three main foci for this workshop: the type systems suitable for databases (especially object-oriented and complex-object databases,) the representation and manipulation of persistent structures, and extensions to deductive databases that allow for more general and flexible programming. Many of the papers describe recent results, or work in progress, and are indicative of the latest research trends in database programming languages. The organizers are extremely grateful for the financial support given by CRAI (Italy), Altaïr (France) and AT&T (USA). We would also like to acknowledge the organizational help provided by Florence Deshors, Hélène Gans and Pauline Turcaud of Altaïr, and by Karen Carter of the University of Pennsylvania

Ausgewählte Kapitel der Implementierung objektorientierter Datenbanksysteme

Objektorientierte Datenbanksysteme bieten gegenüber klassischen Datenbanksysten, wie bspw. den Relationalen Systemen oder den Netzwerk-Systemen, eine erweiterte Funktionalität, die in vielen Anwendungsbereichen benötigt wird. Beispiele für Anwendungen objektorientierter Datenbanksysteme sind technische Informationssysteme Entwurfsdatenbanken oder Multi-Media-Datenbanken. Die erweiterte Funktionalität objektorientierter Datenbanksysteme erfordert neue Implementierungskonzepte. Das Ziel dieses Seminars, das im Sommersemester 1994 am Institut für Programmstrukturen und Daten organisation der Universität Karlsruhe gehalten wurde, ist die Untersuchung ausgewählter Kapitel bei der Implementierung objektorientierter Daten- banksysteme. Das Seminar ist in vier Teile gegliedert. Im ersten Teil wird - quasi aus Benutzersicht - in die Konzepte objektorientierter Datenmodelle eingeführt Aus Implementierungssicht stellen diese Konzepte die Spezifikation für ein zu implementierendes objektorientiertes Datenbanksystem dar. Der zweite Teil beschäftigt sich mit derSpeicherung von Objekten auf dem Hintergrundspeicher sowie mit dem Umgang mit persistenten Objekten zur Laufzeit. In Teil drei werden zwei spezielle Synchronisations-Verfahren vorgestellt, die im Hinblick auf objektorientierte Datenbanksysteme entworfen wurden. In Teil vier sind zwei Themen zusammengefaßt, die einen Überblick geben über Evolution in objektorientierten Datenbanksystemen und über aktive objectorientierte Datenbanksystem