Tableau — Two types of Data Blending

There are 2 types of Data Blending behaviours in Tableau after version 8.0. If you are a beginner in Tableau, you may not notice it at first and find that it is hard to understand the data blending.

Here, we are going to use the Coffee Chain and Office City which normally used in Tableau Training video as an example. We are going to try to do the Data blending on these two data sources, and then list the number of distinct goods/products by the State Dimension.

For the Office City and Coffee Chain, we created a measure — # of Different Goods COUNTD(Goods Name) and # of Different Product COUNTD(Product Name) respectively, which are Non-aggregation values.

Data Blending 1 — All the linked dimensions in the view

All the linked dimensions are in put in the view, in this case, there is only one linked dimension (State Dimension) . Hence, you can see there is no error when you put the Non-aggregation from the secondary source.

Therefore, if you put all the linked dimension to the view , you are able to put the Non-aggregation value from the secondary data source.

Data Blending 2 — Do not include all linked dimensions in view

So now, we remove the State Dimension, the linked dimension from the view. You will notice that the view turn grey in color and the measure from the secondary data source turn to red in color.

And you can find that there is an error message when you mouse over it. It says, “Cannot blend the secondary data source because one or more fields use an unsupported aggregation.”

So, when you encounter the above problem, it is not because you misunderstanding the usage of data blending, it just because it is not available in Tableau.