Live or Extract

When you connect to a file or a server, on the Data Source workplace, at the top right, you have the option to use the Data Source Live or Extract, as you can see in the following screenshot: 

There is a big difference between the two options, so let's see them in detail.

Live

A Live connection creates a direct link between the Tableau Data Source and the database (server or file). It means that, if the data changes, you see the impact in Tableau directly after refreshing the Data Source, or when you reopen the Workbook. 

The problem with a Live connection is that you are dependent on the performance of the database. Large text files, big Excel files, or an unoptimized...