Data Warehouse Modeling Flashcards

In Kimball's dimensional modeling methodology, the design process starts by selecting the:

Answer: Business process to model

Kimball's four-step design begins with choosing the business process, then grain, dimensions, and facts.

Inmon's approach to data warehousing favors:

Answer: A normalized enterprise data warehouse feeding dependent marts

Inmon advocates a top-down, normalized (3NF) enterprise warehouse from which dependent data marts are derived.

A bridge table is used to resolve which kind of relationship between facts and dimensions?

Answer: Many-to-many

Bridge tables handle many-to-many relationships, such as a single bank account with multiple owners.

A degenerate dimension is best described as:

Answer: A dimension key (like an order number) stored in the fact table with no separate dimension table

A degenerate dimension is an identifier such as invoice number kept in the fact table without its own dimension.

A role-playing dimension occurs when:

Answer: A single dimension is referenced multiple times for different roles, like Order Date and Ship Date

A role-playing dimension is one physical table (e.g., Date) referenced multiple times via aliased views for different meanings.

An accumulating snapshot fact table is most appropriate for modeling:

Answer: A process with well-defined milestones, like order fulfillment stages

Accumulating snapshots track a process with multiple milestone dates, updating the same row as stages complete.

A junk dimension is created primarily to:

Answer: Consolidate low-cardinality flags and indicators into one dimension

A junk dimension combines miscellaneous flags and indicators into a single dimension to reduce fact-table clutter.