That looks like an error that came from the db and Tableau Server is just echoing what it "hears". Thus this appears to be something your Actian dba needs to investigate. You may need to tweak your Tableau Data Customization (.tdc) file that governs the ODBC connection if it's something that can be controlled by Tableau (record locking is a common example where a .tdc file is useful).
Can you use the native "Actian Vectorwise"? (I never heard of Actian so I don't know)
So, the reports which are being used by the consumer are are coming out of connections made to Tableau server.
(created data source using the native Actian VW and then published the source to Tableau server and then used it to create the report)
But, inherently it still used the data connection to Actian vectorwise. I did check with the DBA and he tells me that the connection limit is 100(only 4-5 people use these reports, so I'm not sure if those many connections are formed, unless each query uses a conenction)
I'm not sure how to tweak the tableau data customization file though.
I really have no idea
Here's a thought: Could it be that the connections are not being terminated properly and thus are remaining open until the db forces them closed? If true then could the dba change how long a session can remain open before the db forces it closed?