you could potentially query Tableau's internal Postgres database to find the event types that you care about (i.e. 7 - create system user). If you don't have access yet, then see these links: Workgroups Database and Enabling External Access to the Tableau Server Database
select a.created_at, c.name created_by, d.name who
from historical_events a, historical_event_types b, hist_users c, hist_users d
where a.historical_event_type_id = b.type_id
and a.hist_actor_user_id = c.id
and a.hist_target_user_id = d.id
and b.name = 'Create System User'
and created_at >= '2016-07-29'
Thank you so much for your help!
Can you please assist me how can we identify these table & their field details, as I have checked Workgroups Database has different field then the given custom sql.
Also, Could you please help me to get active user and their activity information from repository tables?