A dataset's grain is what a row represents: a session, a click, a conversion, a day per campaign. Knowing it avoids double counting, adding up rates, or joining tables of different granularities: you aggregate to the same grain before joining.
A dataset's grain is what a row represents: a session, a click, a conversion, a day per campaign. Knowing it avoids double counting, adding up rates, or joining tables of different granularities: you aggregate to the same grain before joining.