Microsoft
70-467 · Question #76
70-467 Question #76: Real Exam Question with Answer & Explanation
The correct answer is D. Create one junk dimension.. A junk dimension consolidates multiple low-cardinality flag or indicator columns into a single dimension table, reducing fact table width and the number of dimension foreign keys.
Design a data warehousing solution
Question
You need to slice data by the CouponUsed, OnSale, and Closeout columns. What should you do?
Options
- ACreate one linked dimension for each column.
- BCreate one degenerate dimension.
- CCreate one role-playing dimension.
- DCreate one junk dimension.
Explanation
A junk dimension consolidates multiple low-cardinality flag or indicator columns into a single dimension table, reducing fact table width and the number of dimension foreign keys.
Common mistakes.
- A. A linked dimension is a dimension that is shared across multiple measure groups or cubes; it does not address the problem of storing flag columns from a fact table.
- B. A degenerate dimension holds a key attribute (such as an order number) directly in the fact table with no associated dimension table, which is not applicable to multi-column flag attributes.
- C. A role-playing dimension is a single physical dimension used multiple times in a fact table under different aliases (e.g., Order Date and Ship Date both pointing to a Date dimension), which does not apply to unrelated flag columns.
Concept tested. Junk dimension design for low-cardinality flag attributes
Reference. https://learn.microsoft.com/en-us/azure/architecture/data-guide/relational-data/data-warehousing
Topics
#junk dimension#low-cardinality flags#dimension design#data warehousing
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