Define conformed dimensions.

• A. Dimensions unique to each fact table with no reuse.
• B. Dimensions that contain only descriptive text.
• C. Conformed dimensions are dimensions shared across multiple fact tables with consistent meaning.
• D. A dimension used only for time-based analysis.

Answer: (C)

Conformed dimensions are the shared, consistently defined dimensions used across multiple fact tables in a data warehouse. They appear in more than one fact table with the same meaning, keys, and attributes, so filters and aggregations align when analyzing different measures together. This consistency lets you drill across facts—like analyzing sales and returns—without mismatches because every fact table relies on the same dimension structure and keys.

For example, a Customer dimension might include a surrogate key, name, region, and segment, and that exact structure is used in both the Sales fact and the Returns fact. The keys match and the hierarchies line up, enabling reliable cross-fact analysis and unified reporting.

The other descriptions miss the core idea: creating reuse and a single, consistent meaning across facts. A dimension unique to each fact table prevents cross-analysis; a dimension that is only descriptive text doesn’t address the need for consistent keys and semantics across facts; a time-based dimension is a common kind of dimension, but conformed refers to reuse across multiple fact tables, not just time.