How to do it...

Rather than refreshing the entire extract each time, we can configure a refresh to add only the rows that are new since the previous refresh:

  1. Create a data source using a Text file connection to madrid_2017.csv.
  2. Select the Extract radio button and click on Edit:

  1. Select All rows under Number of Rows to extract:

Incremental refresh can only be defined when you are extracting as Single table with the All rows in database.
  1. Select Incremental refresh and then specify a column that identifies new rows:

  1. Click on OK and save the .hyper file:

  1. Click on Sheet 1 and give the extract a name:

These steps can be used for new or existing extracts. When editing an existing extract, the last refresh is shown.
  1. To verify the latest date loaded, add Date to the Columns shelf.

 

  1. Show the maximum value by right-clicking on Date, choosing Measure, and then selecting Maximum:

  1. Save the workbook and close Tableau.
  2. To simulate the incremental load, copy all the data from Nov.csv and paste it at the end of madrid_2017.csv. Save the file.
  3. Open the workbook and click on Refresh:

  1. Go back to Sheet 1, we now see November 30 as the Max. Date: