One of the basic functionalities of database management systems (DBMSs) is to be able to process declarative user queries. The first generation of object-oriented DBMSs did not provide declarative query capabilities. However, the last decade has seen significant research in defining query models (including calculi, algebra and user languages) and in techniques for processing and optimizing them. Many of the current commercial systems provide at least rudimentary query capabilities. In this chapter we discuss the techniques that have been developed for processing object-oriented queries. Our particular emphasis is on extensible query processing architectures and techniques. The other chapters in this book on query languages and optimization techniques complement this chapter. 1

We define temporal extensions to a uniform, behavioral and functional object model by providing an extensible set of structural and behavioral abstractions to model various notions of time for different applications. We discuss the temporal semantics of inheritance by defining a lifespan behavior on objects in a collection. Finally, we give an elaborative example and show that temporal objects can be queried without adding any extra construct to the underlying query language. 1 Introduction Most of the applications for which object management systems (OMSs) are expected to provide support exhibit some form of temporality. Some examples are the following: in engineering databases, there is a need to identify different versions of a design as it evolves; in multimedia systems, the video images are timed and synchronized with audio; in office information systems, documents are ordered based on their temporal relationships. In this paper we present temporal extensions to the TIGUKAT 1 O...

In this paper, we present an extensible, uniform, behavioral query model and its languages for the TIGUKAT object management system [PÖS92]. The TIGUKAT model is purely behavioral in nature, supports full encapsulation of objects, defines a clear separation between primitive components such as types, classes, collections, behaviors, functions, etc., and incorporates a uniform semantics over objects which makes it a favorable basis for a query model. Queries are modeled as type and behavior extensions to the base object model, thus incorporating queries as an extensible part of the model itself. We present the framework of the complete query model definition that includes the extended types and behaviors, a formal object calculus with safety based on the evaluable class of queries, an equivalent object algebra, an SQL-like ad hoc query language for user-level querying and proof of its completeness.

We present the uniform meta-architecture of the TIGUKAT object model and show how it provides reflection in object management systems. Reflection is the ability for a system to manage information about itself and to access (or reason about) this information through the regular access primitives of the model. The TIGUKAT object model is purely behavioral in nature, supports full encapsulation of objects, defines a clear separation between primitive components such as types, classes, collections, behaviors, functions, etc., and incorporates a uniform semantics over objects. The architecture of its meta-system is uniformly represented within itself, which gives a clean semantics for reflection. 1 Introduction To meet data and information management requirements of new complex applications, object management systems (OMSs) 1 are emerging as the most likely candidates. The general acceptance of this new technology depends on the increased functionality it can provide. Obviously, one meas...

The establishment of a formal object model provides a theoretical foundation to investigate other objectbase features such as query processing. In this report, we present an extensible uniform behavioral object query model for the TIGUKAT object management system. The TIGUKAT object model [PÖS92] is purely behavioral in nature, supports full encapsulation of objects, defines a clear separation between primitive components such as types, classes, collections, behaviors and functions , and incorporates a uniform semantics over objects which makes it a favorable basis for an extensible query model. Every concept that can be modeled in TIGUKAT has the uniform semantics of a first class object with well-defined behavior. Following this semantics, queries are modeled as type and behavioral extensions to the base object model, thus incorporating queries as an extensible part of the model itself. The complete query model definition presented in this report includes: the type and behavior ex...

To meet the data management requirements of new complex applications, object management systems are emerging as the most likely candidate. The general acceptance of this new technology depends on the increased functionality it can provide, and one measurement is the power of its query model. Users of these systems must have a declarative language to formulate queries on "what" information is required without specifying "how" to efficiently retrieve the information. Therefore, the formal query model should define a declarative calculus that can be used to formulate queries to the objectbase and an equivalent procedural algebra to execute them efficiently. In addition, a user-level language should be provided which has the same expressive power as the formal languages. This thesis presents the new TIGUKAT Language that was designed and implemented within the framework of the TIGUKAT project. It is a high level user language which provides declarative access to the underlying objectbase. ...

Objectbase Management Systems are expected to serve data management needs of a wide range of application domains with possibly different query optimization requirements, creating the need of extensibility in the query optimizer to be able to handle the diversity of those requirements. This thesis describes the development of an extensible query optimizer architecture for the TIGUKAT Objectbase Management System, which has a uniform behavioral object model DBMS that represents every system component as a first-class object. Consistent with this philosophy, every component of the optimizer is modeled as a first-class object, providing the ultimate extensibility that the object-oriented paradigm offers. This thesis also describes how the optimizer components are modeled as extensions of the TIGUKAT type system. Acknowledgements I would like to thank my supervisor Dr. M. Tamer Ozsu for suggesting the topic of this research and for his invaluable guidance and support in writing this the...

The object-oriented paradigm of computing has started to have a significant influence on many areas of information and data processing, including database systems. This thesis focuses on the various issues and aspects governing the implementation design and development of the object model for TIGUKAT 1 , an object management system which is intended to be a full featured object-oriented database system on completion. The TIGUKAT object model [25] is behaviorally defined with a uniform object semantics. The model is behavioral in the sense that all access and manipulation of objects is restricted to the application of behaviors on objects, and it is uniform in that every entity within the model has the status of a first-class object. Various implementation design alternatives are discussed and the approaches that were chosen are justified. The ensuing implementation provides a robust kernel around which the rest of the system may be conveniently synthesized. 1 TIGUKAT(tee-goo-kat) i...

We describe the TIGUKAT object management system that is under development at the Laboratory for Database Systems Research of 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 is a first-class object with well-defined behavior. The computational model supported is one of applying behaviors to objects. A query model has been developed for TIGUKAT that is complete with a formal object calculus, an equivalent object algebra and an object SQL language. The uniformity of the model permits modeling queries as objects, opening up the possibility of developing an extensible query optimizer. A prototype implementation of TIGUKAT, including the language and its optimizer is ongoing. 1

Object based systems store information as objects; a storage format that intuitively reflects "real world" requirements. Users access the objects with transactions that take the object base from one stable state to another. Without failures, such as transaction aborts or system crashes, serializability theory and concurrency control algorithms are sufficient to provide correct transaction execution. If failures are present, transaction execution must be controlled so that transaction updates can be undone without affecting the consistency of the database. This thesis provides reliability definitions that govern transaction execution such that correct failure recovery is always possible. The recovery related components of the object based system architecture are depicted. Scheduler algorithms that satisfy the operation ordering criteria of the reliability definitions, are given. To support the reliable schedulers, a novel logging mechanism is introduced. This thesis shows that the datab...