Configure Data Connections
Use the options on the Data Connections tab to configure caching and specify how you want to handle initial SQL statements from data sources.
Views published to Tableau Server are interactive and sometimes have a live connection to a database. As users interact with the views in a web browser, the data that is queried gets stored in a cache. Subsequent visits will pull the data from this cache if it is available. The Data Connections tab is where you configure aspects of caching that will apply to all data connections:
To configure caching, select from one of the following options: :
Refresh Less Often—Data is cached and reused whenever it is available regardless of when it was added to the cache. This option minimizes the number of queries sent to the database. Select this option when data is not changing frequently. Refreshing less often may improve performance.
Balanced—Data is removed from the cache after a specified number of minutes. If the data has been added to the cache within the specified time range the cached data will be used, otherwise new data will be queried from the database.
Refresh More Often—The database is queried each time the page is loaded. The data is still cached and will be reused until the user reloads the page. This option will ensure users see the most up to date data; however, it may decrease performance.
Regardless of how caching is configured, the user can click the Refresh Data button on the toolbar to force the server to send a query and retrieve new data.
When connecting to some data sources, you can specify an initial SQL command that will run when a connection is made to the database, for example, when you open the workbook, refresh an extract, sign in to Tableau Server, or publish to Tableau Server. Initial SQL is not run when your refresh your view. If your data source supports running an initial SQL statement, an Initial SQL link appears in the lower-left corner of the Server Connection dialog box in Tableau Desktop.
For performance or security reasons, some administrators may want to disable this functionality. The Data Connections tab is where you do this:
To disable initial SQL functionality, select the Ignore initial SQL statements for all data sources check box. Workbooks created with initial SQL statements will still open but the initial SQL commands will not be sent.