Support For Queries Research Articles

Enhancing intermodel transformations in a distributed object-oriented database system

A significant amount of research effort has recently been conducted on the fields of distributed databases and database modeling. The prime consequence of these efforts was the adaptation of the object-oriented approach from the programming languages together with advanced query support mechanisms stemming from artificial intelligence concepts. These advanced issues and concepts have, in many respects, exerted influence on the architectural constituents of database management systems and their functionality. In this paper we consider the core features of a new generation of modeling facilities and show how they contribute to the development of advanced translation techniques in a heterogeneous distributed database environment.

The BANG file: A new kind of grid file

A new multi-dimensional file structure has been developed in the course of a project to devise ways of improving the support for interactive queries to database and knowledge bases. Christened the 'BANG' file - a Balanced And Nested Grid - the new structure is of the 'grid file' type, but is fundamentally different from previous grid file designs in that it does not share their common underlying properties. It has a tree-structured directory which has the self-balancing property of a B-tree and which, in contrast to previous designs, always expands at the same rate as the data, whatever the form of the data distribution. Its partitioning strategy both accurately reflects the clustering of points in the data space, and is flexible enough to adapt gracefully to changes in the distribution.

Transportable natural language database update

Natural language database access requires support of both query and update capabilities. Although a great deal of research effort has gone to support natural language database query, little effort has gone to support update. We describe a model of action that supports natural language database update, as well as query, and the implementation of a system that supports the model. A major goal of this research is to design a system that is easily transportable both to different database domains and different database management systems.

A rule-based object/task modelling approach

A rule-based object/task modelling approach is proposed which is characterized by specifying object behaviors and domain rules in terms of object-oriented logic programming, and specifying tasks and meta-rules in terms of network-oriented formalism. In addition the concepts of associations, virtual objects, multiple level integrity control and net expressions are introduced. The object-oriented logic programming system is extended for supporting the semantic modelling, and an explicit control knowledge representation mechanism is developed. This approach may be viewed as a step to the integration of object-oriented programming, logic programming, semantic modelling and event modelling, and to the combination of forward chaining and backward chaining techniques. Therefore, it can provide complementary benefits in deductive query support, integrity control, explicit control knowledge representation and intelligent user interface, and enhance the flexibility and extendibility of knowledge based systems to accommodate applications in multiple domains, towards a generalized, rule-based management of data, action and operational schemes. This approach is being designed and partially implemented on top of System C [Chen 85b] on a VAX computer.