Chapter 6 Working with PDMs
When you import a data warehouse model with external sources from PowerDesigner version 6, the links to external sources are preserved: each external database is converted into a new PDM in the current workspace. This new PDM is automatically declared as a data source for the imported model. Tables and columns in the imported model are automatically mapped to tables and columns in the data source model.
The modeling elements and their relationships are slightly different between previous and current version of PowerDesigner. When you open a version 6 data warehouse model into the current version of PowerDesigner, the following object translations are performed:
| Object in version 6 | Object in current version | Details |
|---|---|---|
| Fact table without fact hierarchy | Fact | A fact is created for each fact table |
| Fact table with fact hierarchy | Fact and cube | A fact and a cube are created for each fact table having a fact hierarchy. The fact is automatically associated with the cube |
| Dimension table | Dimension | Each dimension table directly attached to a fact is converted into a new dimension containing all the attributes of the dimension |
| Attribute | Attribute | attribute |
| Metric | Measure | A measure is created for each metric in the origin model |
| Dimension hierarchy | Dimension | Hierarchies are created in the dimension based on the multidimensional hierarchy |
Each dimension hierarchy is converted into a single dimension.
The dimensions inside the dimension hierarchy are merged into a new dimension. The attributes of these child dimensions become attributes of the new dimension, and, if necessary, their names are prefixed by the name of the new parent dimension.
The conversion process also creates a new hierarchy with the same attributes as the child dimensions copied into the new dimension.
| Version 6 | Current version |
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In the dimension hierarchy, an association is created for each dimension and each dimension hierarchy linked to a fact.
| Version 6 | Current version |
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