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Operators for reclassification queries in a temporal multidimensional model
Operadores para consultas relacionadas con reclasificaciones en un modelo temporal multidimensional
DOI:
https://doi.org/10.15446/ing.investig.v31n1.20531Keywords:
temporal data warehouse, OLAP, reclassification, classification period. (en)bodegas de datos temporales, OLAP, reclasificación, período de clasificación. (es)
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Data warehouse dimensions are usually considered to be static because their schema and data tend not to change; however, both dimension schema and dimension data can change. This paper focuses on a type of dimension data change called reclassification which occurs when a member of a certain level becomes a member of a higher level in the same dimension, e.g. when a product changes category (it is reclassified). This type of change gives rise to the notion of classification period and to a type of query that can be useful for decision-support. For example, What were total chess-set sales during first classification period in Toy category? A set of operators has been proposed to facilitate formulating this type of query and it is shown how to incorporate them in SQL, a familiar database developer language. Our operators' expressivity is also shown because formulating such queries without using these operators usually leads to complex and nonintuitive solutions.
Usualmente las dimensiones de una bodega de datos son consideradas estáticas porque su esquema y datos tienden a no cambiar. Sin embargo, tanto el esquema como los datos de las dimensiones pueden cambiar. Este artículo se enfoca en un tipo de cambio dimensional denominado reclasificación, que ocurre cuando un miembro de un nivel cambia de miembro en un nivel superior de la dimensión, ejemplo, cuando un producto cambia de categoría (es reclasificado). Este tipo de cambios da lugar al concepto período de clasificación y a un tipo de consultas que pueden ser útiles para la toma de decisiones. Verbigracia, ¿cuál fue el total vendido del producto ajedrez durante su primer periodo de clasificación en la categoría juguete? Para facilitar el planteamiento de este tipo de consultas se propone un conjunto de operadores y se muestra como éstos se incorporan en SQL, un lenguaje familiar para los desarrolladores de bases de datos. También se demuestra la expresividad de los operadores propuestos, ya que la formulación de esas consultas sin usar estos operadores usualmente conduce a soluciones complejas y poco intuitivas.
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Copyright (c) 2011 Francisco Moreno, Fernando Arango
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