This would be information that are capture in the logs of the Tableau Server. Which can be analyzed with the Tableau program called Log Shark. Introducing Logshark: Analyze your Tableau Server log files with Tableau | Tableau Software
Note: This has limited support and and is not supported by Tableau Technical Support.
Additionally for investigating fields available in the Postgre SQL data source I would check out the following Tableau Public viz by Ravi Mistry Tableau Public
Hope this helps!