What does the term 'grain' refer to in the context of a Clarity data mart design?

What does the term 'grain' refer to in the context of a Clarity data mart design?

• A. The color of the UI.
• B. The level of detail captured by a fact table; e.g., enrollment-level facts vs patient-level facts.
• C. The language localization.
• D. The number of tables in OLTP.

Answer: (B)

Grain in a data mart design is the level of detail represented by each row in a fact table. It defines what a single fact measures and which keys it carries. For example, with an enrollment-level grain, each row corresponds to one enrollment and would include measures like counts, totals, or durations tied to that enrollment, along with dimension keys such as patient, program, and date. If the grain is patient-level, each row would represent the patient’s individual interaction, allowing different measures and aggregations appropriate to that finer detail. The grain determines which aggregations are possible and how you can roll up or drill down across dimensions. The other items listed—UI color, language localization, or the number of OLTP tables—do not describe the level of detail of a fact table, so they aren’t about grain.

Grain in a data mart design is the level of detail represented by each row in a fact table. It defines what a single fact measures and which keys it carries. For example, with an enrollment-level grain, each row corresponds to one enrollment and would include measures like counts, totals, or durations tied to that enrollment, along with dimension keys such as patient, program, and date. If the grain is patient-level, each row would represent the patient’s individual interaction, allowing different measures and aggregations appropriate to that finer detail. The grain determines which aggregations are possible and how you can roll up or drill down across dimensions. The other items listed—UI color, language localization, or the number of OLTP tables—do not describe the level of detail of a fact table, so they aren’t about grain.