user based trace enable in Cassandra i have created user and role in Cassandra and tracing is enabled. 
but sessions and event table does not capture user info.
below tables gives information about what query has been executed and from which host, but i need user information as well. how we can find that ??

select * from system_traces.events;
 select * from system_traces.sessions;
The system_traces.events and system_traces.sessions tables are used to troubleshoot performance problems.

What you are after is audit capacity. In Apache Cassandra, this is still work in progress, you can follow the work with the following JIRA ticket.