In order to pass the user-agent information from Tableau to Denodo Platform using the Initial SQL option, I would do the following steps:
1. Create an empty table with a field of type 'varchar' on any database (for eg: Oracle) and utilize this table by a creating a base view in the Virtual DataPort Administration Tool.
1. In the Tableau, click on "Initial SQL" option to insert the data into the view by using insert query and select the parameter [TableauServerUser] from the "Insert dropdown" as the value.
* For example: insert into <view name> values([TableauServerUser])
2. Click 'Ok' to execute.
By executing this view in Virtual DataPort, I can able to find the user agent information. The TableauServerUser parameter in Tableau will return the username of the current server user.
Hope this helps!