This triggers a real-time search for all time and is very expensive. Do you really use the data summary page?
I don't use it but the users of the system wonder about it and it's the very first thing they see...
Is there a query which would show the available sourcetypes in the system?
Since Hunk does not support real-time, you will be able to see the available sourcetypes only after you query the Hunk VIX.
On the splunk search type index=YourVirtualIndex and once you see the results, you will see the available souretypes
Try to create a report that looks something like this index=YourVirtualIndex | dedup sourcetype | table sourcetype