MODELS AND SOLUTIONS FOR THE IMPLEMENTATION OF DISTRIBUTED SYSTEMS

Software applications may have different degrees of complexity depending on the problems they try to solve and can integrate very complex elements that bring together functionality that sometimes are competing or conflicting. We can take for example a mobile communications system. Functionalities of such a system are difficult to understand, and they add to the non-functional requirements such as the use in practice, performance, cost, durability and security. The transition from local computer networks to cover large networks that allow millions of machines around the world at speeds exceeding one gigabit per second allowed universal access to data and design of applications that require simultaneous use of computing power of several interconnected systems. The result of these technologies has enabled the evolution from centralized to distributed systems that connect a large number of computers. To enable the exploitation of the advantages of distributed systems one had developed software and communications tools that have enabled the implementation of distributed processing of complex solutions. The objective of this document is to present all the hardware, software and communication tools, closely related to the possibility of their application in integrated social and economic level as a result of globalization and the evolution of e-society. These objectives and national priorities are based on current needs and realities of Romanian society, while being consistent with the requirements of Romania's European orientation towards the knowledge society, strengthening the information society, the target goal representing the accomplishment of e-Romania, with its strategic e-government component. Achieving this objective repositions Romania and gives an advantage for sustainable growth, positive international image, rapid convergence in Europe, inclusion and strengthening areas of high competence, in line with Europe 2020, launched by the European Council in June 2010.information society, databases, distributed systems, e-society, implementation of distributed systems

Оптимизация запросов в системах баз данных на параллельных структурах

В работе представлены наиболее распространенные виды параллельных реляционных СУБД. Определяются понятия времени выполнения запроса (времени отклика системы на запрос) в параллельной системе. Предлагаются эффективные способы вычисления времени отклика.The most widespread types of parallel relational DBMS are presented in paper. The notions of query execution time (response time) are determined in the parallel system. The effective methods of response time calculation are offered

Scalability analysis of declustering methods for multidimensional range queries

Abstract—Efficient storage and retrieval of multiattribute data sets has become one of the essential requirements for many data-intensive applications. The Cartesian product file has been known as an effective multiattribute file structure for partial-match and best-match queries. Several heuristic methods have been developed to decluster Cartesian product files across multiple disks to obtain high performance for disk accesses. Although the scalability of the declustering methods becomes increasingly important for systems equipped with a large number of disks, no analytic studies have been done so far. In this paper, we derive formulas describing the scalability of two popular declustering methods¦Disk Modulo and Fieldwise Xor¦for range queries, which are the most common type of queries. These formulas disclose the limited scalability of the declustering methods, and this is corroborated by extensive simulation experiments. From the practical point of view, the formulas given in this paper provide a simple measure that can be used to predict the response time of a given range query and to guide the selection of a declustering method under various conditions

Administrador visual de entornos BSP

Actualmente es usual encontrar sitios Web que para su funcionamiento proporcionan acceso a bases de datos relacionales y de texto en la modalidad de cliente-servidor. En tales casos, es deseable que en el lado servidor, el administrador de la base de datos sea capaz de procesar lo más rápido posible las consultas producidas por un número grande de clientes generando peticiones de Common Gateway Interface (CGI) a través de lenguajes de script tales como PHP o Perl. En particular, un esquema típico puede ser una configuración donde exista una máquina front-end que reciba requerimientos desde clientes que ejecutan scripts, la cual a su vez envía instrucciones al servidor de bases de datos y espera por una respuesta del mismo. Estas máquinas front-end son las denominadas generadores de consultas. El servidor de base de datos usualmente se comunica con los generadores de consultas por medio de un lenguaje de querying como el SQL. Este servidor, además, puede estar alojado en otra máquina y en realidad puede atender simultáneamente los requerimientos provenientes desde dos o más máquinas generadoras de consultas.Eje: Visualización y Computación gráficaRed de Universidades con Carreras en Informática (RedUNCI

Indexallokation in Parallelen Datenbanksystemen

Die effiziente Nutzung von Zugriffsstrukturen ist eine wichtige Voraussetzung für die performante Durchführung von Datenbankanfragen. Die in Parallelen Datenbanksystemen vom Typ Shared-Nothing übliche, durch die Allokationsstrategie für Relationen weitgehend vorgegebene Indexallokation führt oftmals zu unnötigen I/O-, Verarbeitungs- und Kommunikationskosten. Parallele Shared-Disk Datenbanksysteme bieten durch ihren gemeinsamen Plattenzugriff ein hohes Potential zur flexiblen Allokation von Indexstrukturen. Wir präsentieren eine Klassifikation und eine qualitative Bewertung von Indexallokations-Strategien für diese Architekturklasse, die zeigt, daß sich durch die flexible Wahl von Größen wie Verteilattribut und Verteilgrad die Performanz der parallelen Indexverarbeitung steigern läßt

Методи прискорення обробки великих баз даних із застосуванням багатопроцесорних модулів

The methods of multisequencing of inquiries to databases are offered in the article. The methods allow to achieve optimum balancing of a load of processors with rather low expenses for the interprocessor communications in multiprocessor computing systems based on new modules of expansion. The hardware and algorithms which allow to optimize processing of labour-consuming operations of sorting, connection, sample etc are offered. It allows considerably to reduce time of processing of inquiries in systemВ статье предложены методы распараллеливания запросов к базам данных, что позволяет достичь в многопроцессорных вычислительных системах, базирующихся на новых модулях расширения, оптимальной балансировки загрузки процессоров при относительно низких затратах на межпроцессорные коммуникации. Предложены аппаратные средства и алгоритмы, позволяющие оптимизировать обработку трудоемких операций сортировки, соединения, выборки и др., что позволяет значительно сократить время обработки запросов в системеУ статті запропоновані методи розпаралелювання запитів до баз даних, які дозволяють досягти в багатопроцесорних обчислювальних системах, що базуються на нових модулях розширення, оптимального балансування завантаження процесорів при відносно низьких витратах на,міжпроцесорні комунікації. Запропоновано апаратні засоби та алгоритми, що дозволяють оптимизувати обробку трудомістких операцій сортування, з'єднання, вибірки й ін., що дозволяє значно скоротити час обробки запитів у систем

Analytical response time estimation in parallel relational database systems

Techniques for performance estimation in parallel database systems are well established for parameters such as throughput, bottlenecks and resource utilisation. However, response time estimation is a complex activity which is difficult to predict and has attracted research for a number of years. Simulation is one option for predicting response time but this is a costly process. Analytical modelling is a less expensive option but requires approximations and assumptions about the queueing networks built up in real parallel database machines which are often questionable and few of the papers on analytical approaches are backed by results from validation against real machines. This paper describes a new analytical approach for response time estimation that is based on a detailed study of different approaches and assumptions. The approach has been validated against two commercial parallel DBMSs running on actual parallel machines and is shown to produce acceptable accuracy