I know how to check data distribution per AMP using primary index columns. Easy.
However, I have a table , couple of weeks later new AMPs are added and reconfiguration hasn't been done yet.
How can I determine how many rows are currently belonging to AMPs ?
I don't know if I understood you correctly, but if the reconfig didn't run yet, the new AMPs are unknown to the system. So you run the same query as before...