An overview of data warehouse design approaches and tecbniques

A Data Warehouse (DW) is a database that stores information oriented to satisfy decision-making requests. It ia a database with some particular features concerning the data it contains and its utilisation. The features of DWs cause the DW design process and strategies to be different frome the ones for OLTP Systems. This work presents a brief description of different approaches and techniques that address the DW design problem

Automatic physical database design : recommending materialized views

This work discusses physical database design while focusing on the problem of selecting materialized views for improving the performance of a database system. We first address the satisfiability and implication problems for mixed arithmetic constraints. The results are used to support the construction of a search space for view selection problems. We proposed an approach for constructing a search space based on identifying maximum commonalities among queries and on rewriting queries using views. These commonalities are used to define candidate views for materialization from which an optimal or near-optimal set can be chosen as a solution to the view selection problem. Using a search space constructed this way, we address a specific instance of the view selection problem that aims at minimizing the view maintenance cost of multiple materialized views using multi-query optimization techniques. Further, we study this same problem in the context of a commercial database management system in the presence of memory and time restrictions. We also suggest a heuristic approach for maintaining the views while guaranteeing that the restrictions are satisfied. Finally, we consider a dynamic version of the view selection problem where the workload is a sequence of query and update statements. In this case, the views can be created (materialized) and dropped during the execution of the workload. We have implemented our approaches to the dynamic view selection problem and performed extensive experimental testing. Our experiments show that our approaches perform in most cases better than previous ones in terms of effectiveness and efficiency

Una plataforma basada en metadata para cálculo de vistas en sistemas de información multi-fuentes

Un Sistema de Información Multi- Fuente (MSIS) se compone de un conjunto de fuentes de datos independientes y un conjunto de vistas o consultas que definen los requerimientos de los usuarios. Sus diferencias con los sistemas de información clásicos introducen nuevas actividades de diseño y motiva el desarrollo de nuevas técnicas. En este artículo estudiamos un caso particular de un MSIS: un Data Warehouse (DW) y proponemos un meta-modelo para representar su metadata desde dos puntos de vistas: la representación de los esquemas y las relaciones inter-esquema que permiten calcular una vista a partir de los datos fuentes. El meta-modelo es el centro de una plataforma general para desarrollo de MSIS. La plataforma permite la fácil integración de herramientas de diseño y mantenimiento a través de un modelo de datos común que centraliza el flujo de datos y las rutinas de control de integridad entre las herramientas.Eje: Bases de DatosRed de Universidades con Carreras en Informática (RedUNCI

Elaboration d'entrepôts de données complexes

National audienceIn this paper, we study the data warehouse modelling used in decision support systems. We provide an object-oriented data warehouse model allowing data warehouse description as a central repository of relevant, complex and temporal data. Our model integrates three concepts such as warehouse object, environment and warehouse class. Each warehouse object is composed of one current state, several past states (modelling its detailed evolutions) and several archive states (modelling its evolutions within a summarised form). The environment concept defines temporal parts in the data warehouse schema with significant granularities (attribute, class, graph). Finally, we provide five functions aiming at defining the data warehouse structures and two functions allowing the warehouse class inheritance hierarchy organisation

Inheritance of interorganizational workflows : how to agree to disagree without loosing control?

Intemet-based technology, E-commerce, and the rise of networked virtual enterprises have fueled the need for interorganizational workflows. Although XML allows trading partners to exchange information, it cannot be used to coordinate activities in different organizational entities. Business-to-business processes are hindered by the lack of a common language to support collaboration. This paper describes the P2P (Public-To-Private) approach which addresses some of the problems using a notion of inheritance. The approach consists of three steps: (1) create a common understanding of the interorganizational workfiow by specifying the shared public workflow, (2) partition the public workflow over the organizational entities involved, and (3) for each organizational entity: create a private workflow which is a subclass of the relevant part of the public workfiow. This paper shows that this approach avoids typical anomalies in business-to-business collaboration (e.g., deadlocks and livelocks) and yields an interorganizational workfiow which is guaranteed to realize the behavior specified in the public workflow

Modélisation et extraction de données pour un entrepôt objet

National audienceThis paper describes an object-oriented model for designing complex and time-variant data warehouse data. The main contribution is the warehouse class concept, which extends the class concept by temporal and archive filters as well as a mapping function. Filters allow the keeping of relevant data changes whereas the mapping function defines the warehouse class schema from a global data source schema. The approach take into account static properties as well as dynamic properties. The behaviour extraction is based on the use-matrix concept