Tableau Data Blending

Tips, tricks and fun fact related to Tableau data blending.

1 Primary Data Source
2 Secondary Data Source
3 More than 2 Data Sources
4 Known Limitations

Data Blending is using two or more data sources on the same worksheet.

Primary Data Source

The primary data source is which ever data source you add to the display first.

The primary data source is indicated by a blue check.

All of the data from the primary data source will be added to the worksheet.

Secondary Data Source

All data sources that are added to the display after the first data source become the secondary data source.

The secondary data sources are indicated by an orange check.

Only rows from the secondary data source that have a matching join value with be added to the worksheet (left-join).

More than 2 Data Sources

Known issue: Calculations such as COUNTD, MEDIAN and RAWSQLAGG do not work with more than 2 data sources are used. Troubleshoot Data Blending

Known Limitations

Data blending requires all the data to be loaded onto the Tableau server before any blending or filtering occurs. This is time consuming and resource intensive.

Data blending always and only creates a left-join when used, based on which data source is added to a worksheet first.

You cannot switch the primary and secondary data source, you must start over in a new worksheet using the secondary data source first.

Some calculations become invalid when more than 2 data sources are used.