DESCRIBE DETAIL is the go-to for data size but it only tells you half the story. The delta log and CDF overhead are invisible to it they sit in separate folders on storage and you have to check them directly.Think of it as three buckets for any Delta table. First is your actual data. Second is the delta log which grows quietly over time especially on high-churn tables. Third is the change data folder which only appears when CDF is enabled and captures every insert, update and delete separately.To know your real CDF overhead just compare the change data folder size against your main table size — that ratio tells you exactly what CDF is costing you in storage terms. A table with heavy updates will have a much higher CDF overhead than a mostly append-only table.

So the honest answer is: DESCRIBE DETAIL for data size, storage path inspection for everything else, and SHOW TBLPROPERTIES to confirm which tables actually have CDF switched on before you start comparing.