Type Specific Attributes
What is a type specific attribute?
Type-specific attributes are a type of attribute in dimensional modeling that are used to capture variations in a dimension over time.
What are Core Dimension tables?
Core dimension tables contain the most important dimensions that are commonly used across many different fact tables in a data warehouse.
What is an example of an overlapping custom dimension?
Products sold by a retailer may have some attributes that are common across all products, some that are category-specific, and some that are product-type–specific. A shirt, for example, has a product name and SKU, as does every other product sold.
What do operation systems do?
Operational systems usually support a type-specific view of the data. In some cases, this may be immediately obvious simply by studying the documentation of the operational systems.
What are custom dimension tables?
Custom dimension tables, on the other hand, are used to capture additional information that is specific to a particular business process or application.
What is a generic attribute?
An attribute that can be used across multiple dimensions.
What do analytic systems do for a data warehouse?
The data warehouse must reflect all the ways in which a process is analyzed and measured.
What does it mean for attributes to 'conform'?
This means they must be the same in terms of their structure and content. It also means that the content of these columns must be expressed in a consistent manner.
A Generic design is very ____ for storing information, but not ____ for retrieving information.
flexible
What are the Drawbacks to the Single-Star Approach?
On the technical side, extreme variability in a dimension may result in more attributes than can be managed in a single row. On the Semantic side, a star that consolidates all possible attributes may give rise to nonsensical reports.
What element do both core and custom dimensions share in common?
Surrogate Keys
How would you use an outrigger as an alternative?
A transaction identifier may be used to link a fact table row containing the core facts to a custom extension containing type-specific facts.
When is the issue with consolidating all possible attributes in a single star schema most likely to happen?
This is likely to occur when there are type-specific dimensions and facts.
How do Type 2 dimensions interact wiht core/custom designs?
When the dimension design includes core and custom tables, the change must be applied both to the core dimension table and to any custom dimension tables. This will preserve their interchangeability when joined to a fact table. In the custom table, the old and new rows for the changed item will be visibly different. In the core table, however, the only difference between old and new rows will be the surrogate key value.
How do you use a hierarchy bridge with the core dimension?
The core dimension contains the primary attributes that define the dimension, while the hierarchy bridge is used to link the different levels of the hierarchy together.