In Tableau 9.3, revision history was introduced for workbooks, including the .twb and .twbx files. In Tableau 10.0, revision history was extended to data sources, including the .tds and .tdsx files. By default, Tableau Server's revision history is set to 25. In other words, the past 25 versions of each workbook and data source are retrievable.
In Tableau Desktop, if you attempt to upload a workbook or data source with the same name as a previously uploaded file, Tableau Desktop will display a warning such as Data source is already in use. Publishing will overwrite the existing data source. If you proceed with the upload, revision control will be activated and the previous version of the file will remain accessible as a revision.
To access the revision history for individual workbooks and data sources in Tableau Server, simply select Content...