If you have published a workbook connected to a live data source, the data source will be "live". If you have used an extracted data source then you will need to review Tableau's connecting to data video series the first of which can be found here: Getting Started with Data | Tableau Software .
There are a couple of ways to refresh the data once a workbook is published. A user can do a manual refresh on a worksheet. The server can also have a scheduled extract refresh. Understanding the needs of your users, the demand for fresh vs. stale data, and the size of the data source are all factors that will play into choosing a schedule and method for working with a data source.
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