How to Add Fields to a Tableau Extract. In most cases when a new field is added to a source table that field will be automatically added to the next extract.
New fields added to source tables feeding a Tableau extract in most cases will automatically be added to the extract after its next data refresh.
If a source field was available during the extract creation but was set to hidden and not used in formulas, Tableau will NOT bring in its data automatically.
How to add fields to a Tableau extract on the Tableau Server.
Open Tableau Desktop.
Select Tableau Server under Connect.
Double-click the desired data source from the Search for Data window.
Right-click the data source → Create Local Copy → Save.
Right-click the original data source > Close.
Right-click the locally saved data source → Extract → Remove → Select Remove the extract and delete the extract file → Ok.
Now you should have access to all fields feeding into this data source.
Click the downward arrow button by the Search box → Show Hidden Fields.
Select the field you wish to add from the list under Folders.
If the field is grayed-out, click the down arrow > Unhide.
Click the downward arrow button by the Search box → Show Hidden Fields to clear the option.
Right-click on the locally saved data source → Extract Data → Extract → Save.
Tableau Desktop requires direct access to your data warehouse to perform this task. It might take some time to load the extract data.
Publish the local copy of the data source from Tableau Desktop to Tableau Server.
Right-click the data source again (now it’s an extract) → Publish to Server
Select the appropriate Project and data source name. Desktop should show a “Data source name is already in use.” message.