I believe that some of the desired functionality is available in the Tableau Server ability to create custom admin views for monitoring activities on Tableau Server.
The levels of data needed might need to be adjusted depending on what is being attempted to be done with the data, I would review the 'Collecting Data with the Tableau Server Repository' article prior to connecting directly to the workgroups database.
Additionally,I am including the product help on the use of custom admin views in Tableau Server.
The workgroups database data dictionary gives a good overview of the values that are available in the various tables.
An excellent place to get some ideas of what can be done is to review some of the pre-built views that can be used to monitor Tableau Server traffic and health.
I hope this helps!