Check out the “multi” datasource type at http://druid.io/docs/0.10.1/ingestion/update-existing-data.html. (
It allows you to combine an existing segment with additional source data. Using this, you could iteratively perform delta aggregation of your source data set over and over again.
My mistake, I think firehoses can only be used in realtime nodes – you’ll have to experiment with the functionality defined on the “update-existing-data” documentation page.