Global dimensions is a feature which makes it possible to link else unrelated hierarchies (Different connection/cube) – provided the hierarchies unique names are identical.
When using a criteria on one of the hierarchies in a Global dimension, the criteria is also applied to the other hierarchies in the Global dimension.
Unique names in Analysis Services are prefixed with [Dimension].[Hierarchy], meaning that a unique name belonging to a dimension with the name ‘Period’ cannot immediately be applied in another cube where the dimension is named ‘Posting period’, but the system is made in such a way that the prefix is exchanged before the query reaches Analysis Services.
At present there is no UI for configuring Global dimensions. It all happens in an XML-file: ProgramData\TARGIT\ANTserver\Settings\GlobalDimensions\GlobalDimensions.xml.
In the example Period->Period from Sales cube in DemoData database is linked to Posting Period->Hierarchy in Clothing cube in Casual database (id=”time_hierarchy”). Similar happens with the Month hierarchies (id=”time_month”).
The globalDimension id attribute is not displayed, but must be unique within all the global dimensions . The hierarchies to be linked must be written in the same globalDimension element.