This paper discusses the design and implementation of SEQ, a database system with support for sequence data. SEQ models a sequence as an ordered collection of records, and supports a declarative sequence query language based on an algebra of query operators, thereby permitting algebraic query optimization and evaluation. SEQ has been built as a component of the PREDATOR database system that provides support for relational and other kinds of complex data as well. There are three distinct contributions made in this paper. (1) We describe the specification of sequence queries using the SEQUIN query language. (2) We quantitatively demonstrate the importance of various storage and optimization techniques by studying their effect on performance. (3) We present a novel nested design paradigm used in PREDATOR to combine sequence ‘and relational data.

We propose the notions of virtual schemas and virtual bases as a coherent way of integrating various features in OODB views. A virtual schema is defined based on some existing (real) schema. A virtual base is obtained when a (real) base is attached to a virtual schema. We study the consequences of this simple assumption. In particular, we observe the differences between a real schema and a virtual one. We also consider an extension (that we call generic schemas) where it is necessary to specify several real bases to attach data to a virtual schema. We show how the flexibility provided by virtual schemas can be used to cope with various dynamic features of database systems. 1 Introduction Views are intended to increase the flexibility of database systems and their definition in the object-oriented database (OODB) context comes as a natural extension of the original paradigm. The yet relatively young research on this topic has introduced a large variety of indispensable new features. H...

Abstract. One distinctive characteristic of object-oriented data models over traditional database systems is that they provide more expressive power in schema de nition. Nevertheless, the de ning power of objectoriented models is still somewhat limited, mainly because it is commonly accepted that part of the semantics of the application can be represented within methods. The research work reported in this paper explores the possibility of enhancing the power of object-oriented data models in schema de nition, thus o ering more possibilities to reason about the intension of the database and better supporting data management. We demonstrate our approach by presenting a new data model, called CVL, that extends the usual object-oriented data models with several aspects, including view de nition, recursive structure modeling, navigation of the schema through forward and backward traversal of links (attributes and relations), subsetting of attributes, and cardinality ratio constraints on links. CVL is equipped with sound, complete, and terminating inference procedures, that allow various forms of reasoning to be carried out on the intensional level of the database. 1

This paper concentrates on query unnesting (also known as query decorrelation), an optimization that, even though improves performance considerably, is not treated properly (if at all) by most OODB systems. Our framework generalizes many unnesting techniques proposed recently in the literature and is capable of removing any form of query nesting using a very simple and efficient algorithm. The simplicity of our method is due to the use of the monoid comprehension calculus as an intermediate form for OODB queries. The monoid comprehension calculus treats operations over multiple collection types, aggregates, and quantifiers in a similar way, resulting in a uniform way of unnesting queries, regardless of their type of nesting.

We describe the TIGUKAT objectbase management system that is under development at the Laboratory for Database Systems Research at the University of Alberta. TIGUKAT has a novel object model whose identifying characteristics include a purely behavioral semantics and a uniform approach to objects. Everything in the system, including types, classes, collections, behaviors, functions as well as meta-information, is a first-class object with well-defined behavior. In this way, the model abstracts everything, including traditional structural notions such as instance variables, method implementation and schema definition, into a uniform semantics of behaviors on objects. Our emphasis in this paper is on the object model, its implementation, the persistence model and the query language. We also (briefly) present other database management functions that are under development such as the query optimizer, the version control system and transaction manager.

In this paper, we overview the Object-Protocol Model (OPM) and a suite of data management tools based on OPM. OPM is a data model that allows specifying database structures and queries in terms of objects and protocols specific to scientific (e.g., molecular biology laboratory) applications. Thus, scientific experiments and their resources can be described using OPM in a unified way. OPM data management tools provide facilities for specifying and querying relational databases in terms of OPM constructs, and automatically generate database specifications and queries for implementing OPM on top of commercial relational database management systems (DBMSs). OPM tools increase the efficiency of developing scientific databases using relational DBMSs, while insulating scientists from the underlying DBMSs. Key words: data management tools, object data model, scientific database 1. INTRODUCTION Keeping track and querying data generated by scientific experiments, simulations, and measurements re...

Fibonacci is an object-oriented database programming language characterized by static and strong typing, and by new mechanisms for modeling databases in terms of objects with roles, classes, and associations. A brief introduction to the language is provided to present those features, which are particularly suited to modeling complex databases. Examples of the use of Fibonacci are given with reference to the prototype implementation of the language.

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We argue that, despite a substantial number of proposed and existing new database systems, a suitable database system for software development environments and especially process-centred environments does not yet exist. We do so by reviewing and refining the requirements for such systems in detail based on a number of examples. We then sketch a number of available and archetypical database systems and indicate why they do not meet these requirements. 1 This report has been published in: I. Sommerville and M. Paul, editors, Software Engineering ESEC '93 --- Proc. of the 4 th European Software Engineering Conference, Garmisch Partenkirchen, Germany, volume 717 of Lecture Notes in Computer Science, pages 145--162, Springer 1993. 1 Introduction Software development environments (SDEs) include tools which support most of the software life-cycle phases, i.e. construction and analysis of the corresponding documents and document interdependencies. Sophisticated integrated environments en...

Scientific databases (ScDBs) are used to archive and retrieve data describing objects of scientific inquiry. Since these ScDBs must provide continuous and efficient access to large communities of scientists, they are often developed with reliable commercial relational database management systems (DBMSs) or file systems. However, relational DBMSs and flat files do not provide constructs for representing directly ScDB-specific objects and experimental procedures, and therefore they are often hard to develop, maintain, and explore. In this paper, we present a retrofitting tool for constructing and maintaining ScDB views using an object-oriented data model, and describe our experience with retrofitting ScDBs that have been originally developed using relational DBMSs and file systems. The retrofitting tool is part of a data management toolkit based on the Object-Protocol Model (OPM). The OPM toolkit provides facilities for developing databases defined using OPM and for querying and browsing...