Fully Additive: Revenue, Quantity, Cost

Fully additive measures are the simplest and most common. SUM them across any dimension and the result is meaningful. Revenue summed by product, by region, by month, or by any combination is always correct. This is the default case, and most candidates handle it well. The interview signal is not knowing that revenue is additive. It is knowing where the boundaries are. The Easy Ones: Confirm Them Fast and Move On The Traps: Metrics That Look Additive but Break on Rollup The strongest interview move: when listing measures, proactively separate the additive ones from the trap metrics. 'Revenue and quantity are fully additive. Distinct customer count is not; it requires approximate COUNT DISTINCT (HyperLogLog) for cross-dimension roll-ups. I would not store it as a fact table measure.' What th