Introduction to constraint databases

This book is the first textbook on constraint databases. Its author, together with P. Kanellakis and G. Kuper, introduced constraint databases in 1990 as a powerful generalization of the relational database model. Constraints, such as linear or polynomial equalities and inequalities, are used to finitely represent possibly infinite sets of points. They provide an elegant way to combine classical relational data with, for instance, spatial or temporal data. Since the early 1990s, the topic of constraint databases has received considerable research interest, both theoretical and towards systems development, and has been present at most database conferences during the past decade. It turned out to be a rich area in which a combination of techniques from, e.g., logic, (finite) model theory, algebraic and computational geometry, topology, query languages and symbolic computation are applied. A comprehensive survey of the research results in this field appeared two years ago (Constraint databases, edited by G. Kuper, L. Libkin and J. Paredaens, Springer, 2000). Whereas this survey mainly addresses researchers, the present book aims at making the topic of constraint databases accessible to advanced undergraduate and beginning graduate students and mainly addresses constraint databases from a developer's point of view. This book will certainly contribute to the exposure of constraint databases to a wider audience and hopefully also to its proliferation in a broader database practice. Summary of the book This textbook presents the constraint database model as a powerful extension of the relational model that allows a user or programmer to work easily with infinite data. It covers a wide range of constraint formalisms and shows that the constraint model provides an elegant tool for data modeling and querying in application areas such as geographic information systems (GIS), spatiotemporal data management, bioinformatics, genome databases and computer vision. This book covers a substantial part of constraint-database theory, emphasizes several developer's issues, and presents a number of sample constraint database systems. The author starts by developing the constraint data model from the relational one. Next, he shows how familiar query languages, such as the relational algebra, SQL, and various forms of Datalog carry over to the constraint model. A third broad part of the book focuses on query evaluation and addresses theoretical topics such as quantifierelimination algorithms for several constraint languages and the complexity of query evaluation in these languages. Also more specific data models and query languages are addressed, e.g., for spatiotemporal database applications. Next, the book describes a sample linear constraint database system, a Boolean constraint database system, and a spatiotemporal database system. A last part of the book presents a number of sample applications.