Avatto>>DATA SCIENTIST>>SHORT QUESTIONS>>Tableau Interview Questions
Data Blending is used when there are 2 independent data sources and visualization needs to merge the data from these data sources.

In Data blending, one data source becomes primary and the second data source becomes secondary.

- Data blending is not a join. Join occurs between the tables from the same data source.

-To perform data blending there should be at least one common column between the data sources.

- If a common field does not exist, then edit the relationship between the data sources. To edit relationships, navigate to the menu, and select Data/EditRelationships.

- Data blending can be applied per visualization, it does not carry over to the entire workbook.
The primary data source has a blue checkmark and secondary has an orange checkmark.

How are primary and secondary datasources identified in data blending?

Tableau aggregates data automatically when the measure is placed on the view canvas. Default aggregation is Sum. But it can be changed to any other type of aggregation.