What are level-aware aggregations?

They compute a value at a specified level of detail rather than the visual's level — QuickSight's equivalent of Tableau's LOD expressions.

There are three evaluation points: PRE_FILTER runs before filters, PRE_AGG runs after filters but before the visual's aggregation, and post-aggregate runs at visual level.

sumOver(sum({revenue}), [{customer_id}], PRE_AGG) gives revenue per customer regardless of how the visual is grouped — the standard pattern for customer-level metrics and percent-of-total denominators.