For similarity search in high-dimensional vector spaces (or 'HDVSs'), researchers have proposed a number of new methods (or adaptations of existing methods) based, in the main, on data-space partitioning. However, the performance of these methods generally degrades as dimensionality increases. Although this phenomenon-known as the 'dimensional curse'-is… (More)
Database needs are changing, driven by the Internet and increasing amounts of scientific and sensor data. In this article, the authors propose research into several important new directions for database management systems.
Usually, the first normal form condition of the relational model of data is imposed. Presently, a broader class of data base applications like office information systems is considered where this restriction is not convenient. Therefore, an extension of the relational model is proposed consisting of Non First Normal Form (NF<sup>2</sup>) relations. The… (More)
Processes are increasingly being used to make complex application logic explicit. Programming using processes has significant advantages but it poses a difficult problem from the system point of view in that the interactions between processes cannot be controlled using conventional techniques. In terms of recovery, the steps of a process are different from… (More)
This paper describes a new signature generation method for constructing multi-level signature files to support both relational queries which contain multiple conjunctive (AND) predicates and generic document text queries. We describe the major problems with traditional multi-level signature files and then describe how to build multi-level signature files… (More)
The classical theory of transaction management contains two different aspects, namely concur-rency control and recovery, which ensure serializability and atomicity of transaction executions, respectively. Although concurrency control and recovery are not independent of each other, the criteria for these two aspects were developed orthogonally and as a… (More)
The paper gives an overview of the nested relational model and its two roles in the Darmstadt Database System (DASDBS) project, which was started in 1982 to develop an extensible database architecture supporting a variety of application specific front-ends with a common kernel system. In its first role the nested relational model serves as a model for the… (More)