title: YCSB with mysql Duplicate entry for primary key
body: <p>I try to run ycsb with mysql. Each time that I load and run one of the workloads of YCSB I delete manually the inserted records otherwise I get the message"DuPlicate entry'userx for key 'PRIMARY'". However when I load and run workload d although that I have already trupcate the table I'm facing duplicated primary key issues. Probably in this case when I run workload d it inserts data in the same filed as load does. If I create a table without a primery key I am not sure for the reliability of the ycsb test exeution. Is there a solution for this problem? </p>