Database management systems will continue to manage large data volumes. Thus, efficient algorithms for accessing and manipulating large sets and sequences will be required to provide acceptable performance. The advent of object-oriented and extensible database systems will not solve this problem. On the contrary, modern data models exacerbate it: In order to manipulate large sets of complex objects as efficiently as today’s database systems manipulate simple records, query processing algorithms and software will become more complex, and a solid understanding of algorithm and architectural issues is essential for the designer of database management software. This survey provides a foundation for the design and implementation of query execution facilities in new database management systems. It describes a wide array of practical query evaluation techniques for both relational and post-relational database systems, including iterative execution of complex query evaluation plans, the duality of sort- and hash-based set matching algorithms, types of parallel query execution and their implementation, and special operators for emerging database application domains.

This paper focuses on the version models underlying both commercial systems and research prototypes. It provides an overview and classification of different versioning paradigms. Furthermore, it defines and relates fundamental concepts such as revisions, variants, configurations, and changes. In particular, we focus on intensional versioning, i.e., construction of versions based on configuration rules. Finally,we provide an overview of systems whichhave had significant impact on the development of the SCM discipline, and classify them according to a detailed taxonomy

Concurrency control has been thoroughly studied in the context of traditional database applications such as banking and airline reservations systems. There are relatively few studies, however, that address the concurrency control issues of advanced database applications such as CAD/CAM and software development environments. The

This paper presents a framework for controlling the evolution of complex software systems concurrently developed by teams of software engineers. A general technique for fine-grained revision control of hierarchically structured information, such as programs and documents, is described and evaluated. All levels in the hierarchy are revision controlled, leaves as well as branch nodes. The technique supports sharing of unchanged nodes among revisions, automatic change propagation, and change-oriented representation of differences. Its use in a software development environment is presented, facilitating optimistic check-out of revisions and alternatives, check-in with incremental merge support, visualization of change propagation, and an integrated flexible diff-ing technique providing group awareness for team members. KEYWORDS Software development, version and configuration control, incremental merge, teamware, CSCW, group awareness 1 INTRODUCTION Despite the fact that software systems ...

This article proposes an overview of the Adele system and also discusses other approaches and other systems. While most of our work on Configuration Management is covered, we have deliberately chosen to discuss in greater depth the Work Space aspect and the relationship between the Repository Space and the WSs

Current CSCW applications support one or more modes of cooperative work. The selection of and transition between these modes is usually placed on the users. We built the SEPIA cooperative hypermedia authoring environment supporting a complete set of situations arising during collaborative work and the smooth transitions between them. While early use of the system shows the benefits of supporting smooth transitions between different collaborative modes, it also reveals some deficits regarding parallel work, management of alternative documents, or reuse of document parts. We propose to integrate version support to overcome these limitations. This leads to a versioned data management and an extended user-interface enabling concurrent users to select a certain state of their work, to be aware of related changes, and to cooperate with others either asynchronously or synchronously.

Open-ended activities are characterized by uncertain duration, unpredictable developments, and interactions with other concurrent activities. Like other database applications, they require consistent concurrent access and fault-tolerance, but their unconventional characteristics are incompatible with the conventional database mechanisms of concurrency and failure atomicity. We present the split-transaction and join-transaction operations for restructuring in-progress transactions, as an approach to consistent concurrent access and fault-tolerance for open-ended activities. Split-transaction divides an on-going transaction into two or more transactions that are serializable with respect to each other and all other transactions, and each of the new transactions is later committed or aborted independently of the others. Jointransaction merges two or more transactions that are serializable with respect to each other into a single transaction as if they had always been part of the same tra...

In areas such as finance, marketing, and property and resource management, many database applications manage spatio-temporal data. These applications typically run on top of a relational DBMS and manage spatio-temporal data either using the DBMS, which provides little support, or employ the services of a proprietary system that co-exists with the DBMS, but is separate from and not integrated with the DBMS. This wealth of applications may benefit substantially from built-in, integrated spatio-temporal DBMS support. Providing a foundation for such support is an important and substantial challenge. This paper

Dynamic evolution of workflow models due to process (re)engineering activities and dynamic changing situations of the real process is one of the most important challenges in workflow management. In this paper, we present an approach for the management of evolving workflow specifications which copes with the evolution of a workflow schema and the dynamic modification of workflow instances. The approach is based on the integrated modeling of workflow schema and instance ele- ments, the separated definition of `what to do' and `how to do' in the workflow schema, late binding of workflows at run-time, and the versioning of the workflow schema. On this basis, we support lazy, eager, and selective propagation as well as local customization of instances and their upward propagation. Furthermore, we address the problem of managing consistent configurations of the versioned entities of a workflow schema. In our workflow-specific versioning approach, the consistency of the workflow configuration...

An important yet open problem in workflow management is the evolution of