In many cases, Workgen throws an error when ret does not have the value 0. It would be great which value ret had when the exception was thrown. Example from Testy logs:

Nov 12 20:27:19 ip-172-31-12-172 bash[256516]:     ret = workload.run(connection)
Nov 12 20:27:19 ip-172-31-12-172 bash[256516]: RuntimeError: Table drop failed for 'table:table_vWH9j_mirror' in create_all. 

It would be great to know why the drop failed here.