CONCEPTUAL MODELING
- DWH modeling approaches are as follow
| REQUIREMENT DRIVEN APPROACH | the model is based of user interaction requirements, no knowledge about data sources |
|---|
| DATA DRIVEN APPROACH | the model is based on the data sources available |
| MIXED APPROACH | the requirement analysis refine the model derived by the data sources available |
DIMENSIONAL FACT MODEL
objectives
- create effective documentation
- support for conceptual design
- user friendly environment for queries
- favor communication between the designer and the user
dictionary
| CONCEPT | DESCRIPTION |
|---|
| fact | something relevant to the decision making process |
| measure | numerical property of a fact |
| dimension | it’s a fact property with a finite domain |
| dimensional attribute | dimensions with possible attributes |
| hierarchy | directed tree with dimensional attributes as nodes, it includes a dimension at the root of the tree |
| CONCEPT | DESCRIPTION |
|---|
| PRIMARY EVENT | particular occurrence of a fact identified by a n-ple for each dimension |
| SECONDARY EVENT | identified by a set of n-ple dimensional attribute values, it aggregates a set of primary events |
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