Refreshing Extracts

When the underlying data changes, you can refresh the extract by selecting a data source on the Data menu and then selecting Extract > Refresh. Extracts can be configured to be fully refreshed, replacing all of the data with what’s in the underlying data source, or incrementally refreshed, adding just the new rows since the last refresh.

Full Extracts

By default, extracts are fully refreshed. That means that every time you refresh the extract, all of the rows are replaced with the data in the underlying data source. While this kind of refresh ensures you have an exact copy of what is in the underlying data source, it can sometimes take a long time and be expensive on the database depending on how big the extract is.

If the extract is not set up for incremental extract, selecting refreshing the extract will fully refresh the extract. If you’re publishing the data source to Tableau Server, you can specify the type of refresh in the Scheduling & Passwords dialog box.

Incremental Extracts

Rather than refreshing the entire extract, you can set it up to only add the rows that are new since the last time you extracted data. For example, you may have a data source that is updated daily with new sales transactions. Rather than rebuild the entire extract each day, you can just add the new transactions that occurred that day. Then once a week you may want to do a full refresh just to be sure you have the most up to date data.

Follow the steps below to set up an extract to be incrementally refreshed.

1. Select a data source on the Data menu and then select Extract.
2. In the Extract Data dialog box, select All rows as the number of Rows to extract. Incremental refresh can only be defined when you are extracting all rows in the database. You cannot increment a sample extract.
3. Select Incremental refresh and then specify a column in the database that will be used to identify new rows. For example, if you select a Date field, refreshing will add all rows whose date is after that last time you refreshed. Alternatively, you can use an ID column that increases as rows are added to the database.
   
   
4. When finished, click Extract.

The steps above can be used to define a new extract or configure an existing extract for incremental refresh. If you are editing an existing extract, the last refresh is shown so you can be sure you are updating the extract with the correct data.

If you publish the data source to Tableau Server you can specify a schedule for incremental refresh as well as full refresh in the Schedules & Passwords dialog box.

Extract History

You can see a history of when the extract was refreshed by selecting a data source on the Data menu and then select Extract > History.

The Extract History dialog box shows the date and time for each refresh, whether it was full or incremental, and the number of rows that were added. If the refresh was from a file, it also shows the source file name.