Advanced concepts
Optionality is used to model scenarios for which an association represented in a fact schema is not defined for a subset of events. For instance, in t...
Thu, 1 Jul, 2021 at 12:42 PM
Hierarchies
most commonly include attributes connected to their parents by to-one
associations. However, it may be necessary to also include attributes that...
Thu, 1 Jul, 2021 at 12:41 PM
An incomplete hierarchy is one in which one or more levels of aggregation are missing in some instances (because they are not known or defined). In th...
Thu, 1 Jul, 2021 at 12:33 PM
In a recursive hierarchy, the parent-child relationships among the levels are consistent in semantic terms, but hierarchy instances can have any length. ...
Thu, 1 Jul, 2021 at 12:35 PM
It is often necessary to give additional information on a dimensional attribute in a hierarchy, although it may not be meaningful to use this information as...
Thu, 1 Jul, 2021 at 12:34 PM
Entire portions
of hierarchies are frequently replicated two or more times in fact schemata.
Temporal and geographical hierarchies are classic examples. ...
Thu, 1 Jul, 2021 at 12:36 PM
In a convergence, two or more distinct paths of dimensional attributes within the same hierarchy functionally determine the same dimensional attribute....
Thu, 1 Jul, 2021 at 12:37 PM
A cross-dimensional attribute is a dimensional or descriptive attribute whose value is defined by the combination of two or more dimensional attributes, p...
Thu, 1 Jul, 2021 at 12:41 PM