Is there any ability in Druid to add columns to the pre-aggregated data on an ad-hoc basis?
As I see it, in order for Druid to be able to run an aggregating query, all pre-aggregation calculations must be present in the indexed data source. This means that, if you want to start running a new analytic query that depends on a pre-aggregation calculation (colA * colB), if you don’t have that already pre-calculated as e.g. colC in the data loaded into the Indexing Service, then you would have to add that calculated column to your source data and re-index it.
Is this the case, or is there a clever way around it?