Scaling a Data Warehouse?

When operating on steaming data, you could have millions of billions of events that are flowing throgh dfferent topics. Depending on the view that you write, where is the storage footprint that you have to maintain? So what sort of data do you have tolt hold on to in comparison to the underlying topic, or other sources of data that you connect to? The answer to this is very so it depends on a word you use, which you have to do. And i can tell you both what we have to do and what we happen to do at the moment.