Refresh Data Sources
If you are connected to a data source that has been modified, you can immediately update Tableau Desktop with the changes by selecting a data source on the Data menu and then selecting Refresh.
Not every connection will behave in the same way. There are three primary connection types: Live Connection, Extract, and Published Data Source. The type of connection is displayed by the icon next to your data source in the Data Pane.
A live connection sends queries to the database and updates the view depending on the results. However, the specific fields queried are defined when the connection is initially created. Refreshing the data source will update any new or changed fields. For more information, see Connect to Your Data.
Refreshing an extract will query the data source the extract was created from and rebuild the extract. This process might take some time, depending upon the size of the extract. For more information, see Extract Your Data.
Published Data Source
When connected to a Published Data Source, the data source can be either a live connection or an extract. Selecting the Data Source tab will display whether the Published Data Source is a live connection or an extract. If the data source is an Extract, all refreshes of the extract are managed by Tableau Server and can only be refreshed by the server.
For more information, see Best Practices for Published Data Sources.
Changes to underlying data
If a field that is used in a Tableau worksheet is removed from the underlying data of the data source and then the data source is refreshed, a warning message displays indicating that the field will be removed from the view and the worksheet will not display correctly because of the missing field.
If the underlying data changes—for example, if new fields or rows are added, data values or field names are changed, or data is deleted, Tableau will reflect those changes the next time you connect to the data source. However, because Tableau Desktop queries the data and does not import the data, you can immediately update Tableau to reflect the data modifications without disconnecting, provided the changes have been saved in the underlying data first.
Note about web authoring (Tableau Online and Tableau Server): If you connect to a published flat file (Excel or text) directly in Tableau Online or Tableau Server, that data will not be refreshed even if it’s modified. If your data is in an on-premises server and is published to the web through Tableau Desktop, it will be rendered as an extract and won’t be refreshed. If you need to keep data published through Tableau Desktop fresh on the web, you can use Tableau Bridge. To learn more about these requirements, see Keep Data Fresh and Use Tableau Bridge to Keep Tableau Online Data Fresh