Performance of VIDEBAS in an operational environment

VIDEBAS is a relational database management system in which a database consists of two parts, namely a “real-only” and an “update” part. The first part remains unmodified until the next reorganization and exploits redundancy to achieve fast access to data. A prototype of VIDEBAS has been built. In this paper a performance comparison between this relational system and a DBTG-system (UDS) is made. The used external memory and the number of page accesses to retrieve and update tuples is estimated. Although it is commonly assumed that in an operational environment relational systems are slower than network systems the opposite appears. On the other hand UDS needs less external memory

Control versus Data Flow in Parallel Database Machines

The execution of a query in a parallel database machine can be controlled in either a control flow way, or in a data flow way. In the former case a single system node controls the entire query execution. In the latter case the processes that execute the query, although possibly running on different nodes of the system, trigger each other. Lately, many database research projects focus on data flow control since it should enhance response times and throughput. The authors study control versus data flow with regard to controlling the execution of database queries. An analytical model is used to compare control and data flow in order to gain insights into the question which mechanism is better under which circumstances. Also, some systems using data flow techniques are described, and the authors investigate to which degree they are really data flow. The results show that for particular types of queries data flow is very attractive, since it reduces the number of control messages and balances these messages over the node

Real options and scenario planning as a way to gain insight into flexibility in health care real estate management, a first exploration

Real estate management in health care faces many uncertainties, and more specific in the Netherlands even more because of changing regulations regarding\ud the financing of capital costs. Therefore we propose, based on literature and a\ud survey, to use scenario planning in combinations with the real option approach to deal with these uncertainties. The survey shows that limited use is made of future uncertainties and options for flexibility in the responded Dutch hospitals. Real options provide insight for real estate managers into opportunities for flexibility when making strategic decisions in real estate management, such as choosing for a building organisation form

On the Selection of Optimal Index Configuration in OO Databases

An operation in object-oriented databases gives rise to the processing of a path. Several database operations may result into the same path. The authors address the problem of optimal index configuration for a single path. As it is shown an optimal index configuration for a path can be achieved by splitting the path into subpaths and by indexing each subpath with the optimal index organization. The authors present an algorithm which is able to select an optimal index configuration for a given path. The authors consider a limited number of existing indexing techniques (simple index, inherited index, nested inherited index, multi-index, and multi-inherited index) but the principles of the algorithm remain the same adding more indexing technique

The relationship between IR and multimedia databases

Modern extensible database systems support multimedia data through ADTs. However, because of the problems with multimedia query formulation, this support is not sufficient.\ud \ud Multimedia querying requires an iterative search process involving many different representations of the objects in the database. The support that is needed is very similar to the processes in information retrieval.\ud \ud Based on this observation, we develop the miRRor architecture for multimedia query processing. We design a layered framework based on information retrieval techniques, to provide a usable query interface to the multimedia database.\ud \ud First, we introduce a concept layer to enable reasoning over low-level concepts in the database.\ud \ud Second, we add an evidential reasoning layer as an intermediate between the user and the concept layer.\ud \ud Third, we add the functionality to process the users' relevance feedback.\ud \ud We then adapt the inference network model from text retrieval to an evidential reasoning model for multimedia query processing.\ud \ud We conclude with an outline for implementation of miRRor on top of the Monet extensible database system

Commercialization of agriculture under population pressure: effects on production, and nutrition in Rwanda

Agricultural policy Rwanda., Produce trade Government policy Rwanda., Exports Rwanda., Nutrition policy Rwanda., Food supply Rwanda., Rwanda Population.,

On the selection of secondary indices in relational databases

An important problem in the physical design of databases is the selection of secondary indices. In general, this problem cannot be solved in an optimal way due to the complexity of the selection process. Often use is made of heuristics such as the well-known ADD and DROP algorithms. In this paper it will be shown that frequently used cost functions can be classified as super- or submodular functions. For these functions several mathematical properties have been derived which reduce the complexity of the index selection problem. These properties will be used to develop a tool for physical database design and also give a mathematical foundation for the success of the before-mentioned ADD and DROP algorithms

The Acoustics of Social Learning: Designing learning processes that contribute to a more sustainable world.

Learning for Sustainable Development contributes to a society in which citizens, companies, organisations, and authorities learn about sustainable development and are desiring, willing, and able to contribute to it

TOPYDE: A Tool for Physical Database Design

We describe a tool for physical database design based on a combination of theoretical and pragmatic approaches. The tool takes as input a relational schema, the workload defined on the schema, and some additional database characteristics and produces as output a physical schema. For the time being, the tool is tuned towards Ingres

Effect of cleaning /disinfection strategies on helminth infections in finishing pigs

Ascaris suum is the most prevalent helminth on organic pig farms (Carstensen et al., 2002) and is transmitted mainly via the faeces. The use of anthelmintics does not fit in the organic principles and preventive measures are promoted. This project focused on assessing the efficacy of a cleaning protocol for the dunging area of pens on Ascaris s. transmission to pigs. In 4 batches with 8 identical pens for 15 pigs each (n=480 pigs) 6 pigs per pen were orally infected with Ascaris s. The other pigs can be earliest infected at 10 weeks and half of the pens were thoroughly cleaned at that time. Affected livers and egg counts in the manure had to show if this cleaning protocol keeps the non infected animals free of Ascaris s. The results show no effect of the cleaning protocol on the non infected pigs. These pigs had 57% damaged livers in both treatment and 50% had positive egg counts in the manure. The conclusion is that pen hygiene does not contribute to a reduction of Ascaris s. infections