Sessions in rollback may appear to have logged off in both DBC.LogOnOffV and DBC.AccessLogV, but this is not always the case. The logoff would depend on the manner in which the job was aborted. If you specify one of the following:
ABORT SESSION hostid.username LOGOFF ABORT SESSION *.username LOGOFF ABORT SESSION hostid.* LOGOFF
then the LOGOFF option would terminate the session.
Without it, the session should continue until the abort completes or the Supervisor issues a LOGOFF request. Unless an SQL job is explicitly coded to do otherwise, a session will also appear to have logged off if the system has undergone a restart.
The rollback or abort is independent of the session. It is actually handled by a completely different mechanism with internally allocated AMP worker tasks.