Unable to Use RAWSQL Pass-Through Functions with Published Data Sources

Unable to use RAWSQL pass-through functions in calculated fields when connected to a published data source.
 

Cause

This behavior is by design.

The Tableau data server masks the specifics of the backing data source and instead presents a general relational interface for Tableau Desktop to query. Clients of this data model are not able to alter the published data model. As a result, Tableau Desktop users cannot use any functionality present in the live database connection, including using RAWSQL functions in calculated fields.