Center For Distributed Interactive Simulation Testing: Volume I Technical Proposal

Proposal for creating a Center for distributed interactive simulation testing which would provide facilities and capabilities for conducting conformance, interoperability and performance testing for the evolving Department of Defense-sponsored Military Standard for Distributed Interactive Simulation

A Survey of Traditional and Practical Concurrency Control in Relational Database Management Systems

Traditionally, database theory has focused on concepts such as atomicity and serializability, asserting that concurrent transaction management must enable correctness above all else. Textbooks and academic journals detail a vision of unbounded rationality, where reduced throughput because of concurrency protocols is not of tremendous concern. This thesis seeks to survey the traditional basis for concurrency in relational database management systems and contrast that with actual practice. SQL-92, the current standard for concurrency in relational database management systems has defined isolation, or allowable concurrency levels, and these are examined. Some ways in which DB2, a popular database, interprets these levels and finesses extra concurrency through performance enhancement are detailed. SQL-92 standardizes de facto relational database management systems features. Given this and a superabundance of articles in professional journals detailing steps for fine-tuning transaction concurrency, the expansion of performance tuning seems bright, even at the expense of serializabilty. Are the practical changes wrought by non-academic professionals killing traditional database concurrency ideals? Not really. Reasoned changes for performance gains advocate compromise, using complex concurrency controls when necessary for the job at hand and relaxing standards otherwise. The idea of relational database management systems is only twenty years old, and standards are still evolving. Is there still an interplay between tradition and practice? Of course. Current practice uses tradition pragmatically, not idealistically. Academic ideas help drive the systems available for use, and perhaps current practice now will help academic ideas define concurrency control concepts for relational database management systems

Single-Site And Distributed Optimistic Protocols For Concurrency Control

The authors consider that, in spite of their advantage in removing the overhead of lock maintenance and deadlock handling, optimistic concurrency control methods have been applied less in practice than locking schemes. Two complementary approaches are introduced that may help render the optimistic approach practically viable. For the high-level approach, integration schemes can be utilized so that the database management system is provided with a variety of synchronization methods each of which can be applied to the appropriate class of transactions. The low-level approach seeks to increase the concurrency of the original optimistic method and improve its performance. The author examines the low-level approach in depth, and presents algorithms that aim at reducing back-ups and improve throughput. Both the single-site and distributed networks are considered. Optimistic schemes using time-stamps for fully duplicated and partially duplicated database networks are presented, with emphasis on performance enhancement and on reducing the overall cost of implementation

Métricas de performance en administración de bases de datos distribuidas en redes LAN y WAN

El presente trabajo presenta un estudio de las principales características que debe seguir un esquema de replicación de datos. A partir de cada una de las características en juego, se definieron modelo de simulación que permite evaluar el comportamiento posible del modelo de datos y su esquema de replicación. Con los resultados obtenidos es posible evaluar distintas alternativas de solución y, de esa forma, aproximarse al esquema que mejor se adecue para el problema que se está estudiandoFacultad de Informátic

An Introduction to Database Systems

This textbook introduces the basic concepts of database systems. These concepts are presented through numerous examples in modeling and design. The material in this book is geared to an introductory course in database systems offered at the junior or senior level of Computer Science. It could also be used in a first year graduate course in database systems, focusing on a selection of the advanced topics in the latter chapters