Identifying New Directions in Database Performance Tuning

Database performance tuning is a complex and varied active research topic. With enterprise relational database management systems still reliant on the same set-based relational concepts that defined early data management products, the disparity between the object-oriented application development model and the object-relational database model, called the object-relational impedance mismatch problem, is addressed by techniques such as object-relational mapping (ORM). However, this has resulted in generally poor query performance for SQL developed by object applications and an irregular fit with cost-based optimisation algorithms, and leads to questions about the need for the relational model to better adapt to ORM-generated queries. This paper discusses database performance optimisation developments and seeks to demonstrate that current database performance tuning approaches need re-examination. Proposals for further work include exploring concepts such as dynamic schema redefinition; query analysis and optimisation modelling driven by machine learning; and augmentation or replacement of the cost-based optimiser model

Information technology and distance learning aspects of materials databases

Distance learning is a flourishing area, with the number of programs, provided via remote delivery, increasing daily. At the same time, however, progress in the field of accessibility and support for learners, who want to pursue education and training in the area of materials science and engineering, has not always kept pace. An individual interested in taking a materials course, or in simply finding out what is available, may find himself/herself forced to locate and then plough through many unwieldy online course listings. This may discourage many learners from pursuing the distance learning option. In recent years, more and more distance learning databases have been developed and made available on the World Wide Web. These distance-learning databases are aimed to offer an information pool on many courses and programs that are available online and to cater for users' specific needs of locating information. This need is equally applicable to the area of materials science and engineering. The purpose of this current research has been to explore Information and Technology aspects of materials databases and closely study distance learning aspects. [Continues.

Performance investigation into selected object persistence stores

The current popular, distributed, n-tiered, object-oriented application architecture pro- vokes many design debates. Designs of such applications are often divided into logical layer (or tiers) - usually user interface, business logic and domain object (or data) layer, each with their own design issues. In particular, the latter contains data that needs to be stored and retrieved from permanent storage. Decisions need to be made as to the most appropriate way of doing this - the choices are usually whether to use an object database, to communicate directly with a relational database, or to use object-relational mapping (ORM) tools to allow objects to be translated to and from their relational form. Most often, depending on the perceived profile of the application, software architects make these decisions using rules of thumb derived from particular experience or the design patterns literature. Although helpful, these rules are often highly context-dependent and are of- ten misapplied. Research into the nature and magnitude of 'design forces' in this area has resulted in a series of benchmarks, intended to allow architects to understand more clearly the implications of design decisions concerning persistence. This study provides some results to help guide the architect's decisions. The study investigated and focused on the <i.performance of object persistence and com- pared ORM tools to object databases. ORM tools provide an extra layer between the business logic layer and the data layer. This study began with the hypothesis that this extra layer and mapping that happens at that point, slows down the performance of object persistence. The aim was to investigate the influence of this extra layer against the use of object databases that remove the need for this extra mapping layer. The study also investigated the impact of certain optimisation techniques on performance. A benchmark was used to compare ORM tools to object databases. The benchmark provided criteria that were used to compare them with each other. The particular benchmark chosen for this study was OO7, widely used to comprehensively test object persistence performance. Part of the study was to investigate the OO7 benchmark in greater detail to get a clearer understanding of the OO7 benchmark code and inside workings thereof. Included in this study was a comparison of the performance of an open source object database, db4o, against a proprietary object database, Versant. These representatives of object databases were compared against one another as well as against Hibernate, a popular open source representative of the ORM stable. It is important to note that these applications were initially used in their default modes (out of the box). Later some optimisation techniques were incorporated into the study, based on feedback obtained from the application developers. There is a common perception that an extra layer as introduced by Hibernate nega- tively impacts on performance. This study showed that such a layer has minimal impact on the performance. With the use of caching and other optimisation techniques, Hibernate compared well against object databases. Versant, a proprietary object database, was faster than Hibernate and the db4o open source object database. CopyrightDissertation (MSc)--University of Pretoria, 2010.Computer Scienceunrestricte

The application of Software Metrics to the area of Formal Specification

In this work our aim has been to investigate the application of software metrics to the area of formal specification. We first look at the nature of Formal Methods and those most commonly in use. This suggests the scope for the type of specifications that should come under investigation. Metrics and the nature of measurement become an important consideration as we discuss how to assess Formal Methods themselves and their impact on software development. We look at the work already done in software metrics to see if parallels can be drawn with the proposed work on formal specification. To establish current knowledge about the use and effectiveness of Formal Methods we investigate to see how their benefits had been assessed by two major surveys. Further information on the impact of the methods is obtained by analysing the results from a series of case studies. We build on work done in a previous study to investigate and compare attributes of three formal specification notations. This gives valuable insights into possible attributes, the way measurements might be made and possible metrics to establish. Drawing together the knowledge and experiences gained from the background research we design three experiments to look at metrics for comprehensibility in formal specifications. The experiments together with their results and statistical analysis are described. The main findings show that the variable names, comment levels and structure of Z specifications have an effect on their comprehensibility

Relational Set Theory

This article presents a relational formalization of axiomatic set theory, including socalled ZFC and the anti-foundation axiom (AFA) due to P. Aczel. The relational framework of set theory provides a general methodology for the fundamental study on computer and information sciences such as theory of graph transformation, situation semantics and analysis of knowledge dynamics in distributed systems. To demonstrate the feasibility of relational set theory some fundamental theorems of set theory, for example, CantorBernstein -Schroder theorem, Cantor&apos;s theorem, Rieger&apos;s theorem and Mostowski&apos;s collapsing lemma are proved. 1 Introduction The study on (binary) relations on sets has been begun together with the pioneering works of set theory and since then theory of relations has been extensively investigated by many mathematicians from the view points of logic, algebra, topology and computer science. For more detailed history of studies on relations the reader refer to R.D. Muddux [14] and..

Relational Set Theory

This article presents a relational formalization of axiomatic set theory, including so-called ZFC and the anti-foundation axiom (AFA) due to P. Aczel. The relational frame-work of set theory provides a general methodology for the fundamental study on computer and information sciences such as theory of graph transformation, situation semantics and analysis of knowledge dynamics in distributed systems. To demonstrate the feasibility of relational set theory some fundamental theorems of set theory, for example, Cantor-Bernstein-Schröder theorem, Cantor's theorem, Rieger's theorem and Mostowski's collapsing lemma are proved

Relational Set Theory

This article presents a relational formalization of axiomatic set theory, including so-called ZFC and the anti-foundation axiom (AFA) due to P. Aczel. The relational frame-work of set theory provides a general methodology for the fundamental study on computer and information sciences such as theory of graph transformation, situation semantics and analysis of knowledge dynamics in distributed systems. To demonstrate the feasibility of relational set theory some fundamental theorems of set theory, for example, Cantor-Bernstein-Schröder theorem, Cantor\u27s theorem, Rieger\u27s theorem and Mostowski\u27s collapsing lemma are proved