Anfrageoptimierung in Data Warehouses durch Verwendung voraggregierter Views

In der vorliegenden Diplomarbeit wird ein Verfahren vorgestellt, mit dem Aggregatanfragen an ein relational verwaltetes Data Warehouse optimiert werden. Mittels voraggregierter Relationen, welche das Ergebnis von Aggregatanfragen sind und materialisierte Views genannt werden, werden Anfragen an das Data Warehouse analysiert und umgeschrieben. Dafür müssen Metadaten über die Views vorliegen, die in einem umgesetzten Relationenschema verwaltet werden. Darüber hinaus wird eine Kostenfunktion definiert, mit der entschieden wird, welche materialisierte View zur Optimierung verwendet werden soll. Weiterhin wird ein Verfahren erläutert, mit dem materialisierte Views bei Änderungen der Daten des Data Warehouses aktualisiert werden. The diploma thesis presents a technique for optimizing aggregation-queries to relational data warehouses. With the use of preaggregated relations, which are the results of former aggregation-queries and named as materialized views, queries to data warehouses are analyzed and reformulated. Therefore metadata are needed, which are stored in an implemented relation-schema. Furthermore a cost function is defined, that determines the materialized view used for optimization. A maintenance technique for updating materialized views after changing data of the data warehouse is also presented

Automatisierte Modelladaptionen durch Evolution - (R)ELaX in the Garden of Eden

Die in diesem Artikel vorgestellte Methode zur XML-Schemaevolution automatisiert ebenenübergreifend Veränderungen ausgehend von einem konzeptionellen Modell über XML-Schemata bis hin zu XML-Dokumenten; Schwerpunkt dabei ist die Entwicklung der Evolutionssprache ELaX (Evolution Language for XML-Schema)

XML Schema Transformations - The ELaX Approach

In this article the transformation language ELaX (Evolution Language for XML-Schema) for modifying existing XML Schema is introduced. This domain-specific language is an answer to the dire necessity to handle modifications on an XML Schema and to express such modifications formally. The language has a readable, simple, base-model-oriented syntax, but it's able to express all possible complex transformations by using add, delete and update operations. A small subset of operations of the whole language is presented and exemplarily illustrated by dealing with a real life XML Schema of the WSWC (Western States Water Council). Finally, the idea of integrating an ELaX interface into a developed research prototype for dealing with the co-evolution of corresponding XML documents is presented

XML-Schemaevolution - Änderung eines XML-Schemas mit automatisierter Adaption assoziierter XML-Dokumente

Die XML-Schemaevolution löst das Gültigkeitsproblem von XML-Dokumenten, das bei der Änderung des zugeordneten XML-Schemas auftreten kann. Ausgehend von dem konzeptuellen Modell EMX, der Transformationssprache ELaX, sowie deren Optimierungsalgorithmus ROfEL, wird ein Mechanismus vorgestellt, mit dem automatisiert bei instanzverändernden Modell- bzw. Schemaanpassungen Transformationsschritte aus der geloggten Nutzerinteraktion erzeugt werden. Mit diesen Schritten wird das DOM eines XML-Dokuments adaptiert. Der Forschungsprototyp CodeX wird diesbezüglich als Demonstrator ebenso vorgestellt

A Conceptual Model for the XML Schema Evolution

In this article the conceptual model EMX (Entity Model for XML-Schema) for dealing with the evolution of XML Schema (XSD) is introduced. The model is a simplified representation of an XSD, which hides the complexity of XSD and offers a graphical presentation. For this purpose a unique mapping is necessary which is presented as well as further information about the visualization and the logical structure. A small example illustrates the relationships between an XSD and an EMX. Finally, the integration into a developed research prototype for dealing with the coevolution of corresponding XML documents is presented

Optimization of Sequences of XML Schema Modifications - The ROfEL Approach

The transformation language ELaX (Evolution Language for XML-Schema [16]) is a domain-specific language for modi-fying existing XML Schemas. ELaX was developed to ex-press complex modifications by using add, delete and up-date statements. Additionally, it is used to consistently log all change operations specified by a user. In this pa-per we present the rule-based optimization algorithm ROfEL (Rule-based Optimizer for ELaX) for reducing the number of logged operations by identifying and removing unneces-sary, redundant and also invalid modifications. This is an essential prerequisite for the co-evolution of XML Schemas and corresponding XML documents. 1

XML Schema Transformations - The ELaX Approach

In this article the transformation language ELaX (\underlineEvolution \underlineLanguage for \underlineXML-Schema) for modifying existing XML Schemas is introduced. This domain-specific language was developed to fulfill the crucial need to handle modifications on an XML Schema and to express such modifications formally. The language has a readable, simple, base-model-oriented syntax, but it is able to also express more complex transformations by using add, delete and update operations. A small subset of operations of the whole language is presented and illustrated partially by dealing with a real life XML Schema of the WSWC (\underlineWestern \underlineStates \underlineWater \underlineCouncil). Finally, the idea of integrating an ELaX interface into an existing research prototype for dealing with the co-evolution of corresponding XML documents is presented