Specifying Aggregation Functions in Multidimensional Models with OCL
Résumé
Multidimensional models are at the core of data warehouse systems, since they allow decision makers to early define the relevant information and queries that are required to satisfy their information needs. The use of aggregation functions is a cornerstone in the definition of these multidimensional queries. However, current proposals for multidimensional modeling lack the mechanisms to define aggregation functions at the conceptual level: multidimensional queries can only be defined once the rest of the system has already been implemented, which requires much effort and expertise. In this sense, the goal of this paper is to extend the Object Constraint Language (OCL) with a predefined set of aggregation functions. Our extension facilitates the definition of platform-independent queries as part of the specification of the conceptual multidimensional model of the data warehouse. These queries are automatically implemented with the rest of the data warehouse during the code-generation phase. The OCL extensions proposed in this paper have been validated by using the USE tool.