YAM^2: a multidimensional conceptual model
ABRSTRACT<br/>This thesis proposes YAM^2, a multidimensional conceptual model for OLAP(On-Line Analytical Processing). It is defined as an extension of UML (Unified Modeling Language). The aim is to benefit from Object-Oriented concepts and relationships to allow the definition of semantically...
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| Formato: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2002 |
| País: | España |
| Recursos: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/6637 |
| Acesso em linha: | http://www.tdx.cat/TDX-1004102-091640 http://hdl.handle.net/10803/6637 https://dx.doi.org/10.5821/dissertation-2117-93948 |
| Access Level: | acceso abierto |
| Palavra-chave: | Disseny multidimensional 1203. Ciencia dels ordinadors 004 68 |
| Resumo: | ABRSTRACT<br/>This thesis proposes YAM^2, a multidimensional conceptual model for OLAP(On-Line Analytical Processing). It is defined as an extension of UML (Unified Modeling Language). The aim is to benefit from Object-Oriented concepts and relationships to allow the definition of semantically rich multi-star schemas. Thus, the usage of Generalization, Association, Derivation, and Flow relationships (in UML terminology) is studied.<br><br/>An architecture based on different levels of schemas is proposed and the characteristics of its different levels defined. The benefits of this architecture are twofold. Firstly, it relates Federated Information Systems with Data Warehousing, so that advances in one area can also be used in the other. Moreover, the Data Mart schemas are defined so that they can be implemented on different Database Management Systems, while still offering a common integrated vision that allows to navigate through the different stars.<br><br/>The main concepts of any multidimensional model are facts and dimensions. Both are analyzed separately, based on the assumption that relationships between aggregation levels are part-whole (or composition) relationships. Thus, mereology axioms are used on that analysis to prove some properties.<br><br/>Besides structures, operations and integrity constraints are also defined for YAM^2. Due to the fact that, in this thesis, a data cube is defined as a function, operations (i.e. Drill-across, ChangeBase, Roll-up, Projection, and Selection) are defined over functions. Regarding the set of integrity constraints, they reflect the importance of summarizability (or aggregability) of measures, and pay special attention to it. |
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