Consider a measure in a cube:
Consider that a fact table F is supplying data to this cube, which has the column "revenue"
We run a query:
Lens complains the that the "columnsMissingDefaultAggregate". This happens because we are querying for "count" when the default_aggr defined for the measure in the cube is SUM. It runs fine if the query is for sum(revenue).
This is then fixed by setting the property "cube.fact.is.aggregated" = false on the fact table F.
IMO this behaviour of "is aggregated fact" is not documented properly and will leave many other users confused. Lets make it more obvious by way of having it as part of fact schema spec or document it well.