Choosing the Grain

One row per what? A pharmacy chain wants three numbers from its data. It wants the packs of each drug a store dispensed each day, the packs on the shelf at the end of each day, and the time each prescription took from the counter to the customer. All three come from the same store. Each one, however, is easiest to answer from a table whose rows mean something different.

The level of detail that one row of a fact table stands for (its grain) was defined in Facts Dimensions and Grain