Data blending takes place when you mix information on one worksheet from several information sources. The information on common sizes is combined. Data Blending does not generate row levels, nor is it a means of adding fresh sizes or rows.  We use this when we want to collect data from various sources and use the same worksheet. We don't have any joints as such, but only offer references to columns, such as main and external main relationships. For instance, the two data sources may share a date field in the combination of actual and target sales data.  You must use the Date field on the sheet. Afterward, Tableau automatically links areas that have the same name if you move to a secondary source in the information window. You can identify a custom connection between areas if they do not have the same name. A default mix can look like a left outside join. The correct left and internal joints are likely to be reproduced by filtering nulls and turning the main source.