Tableau Cloud Full-outer join in the physical layer (default sort)

I am taking the Tableau Business Intelligence Analyst course, the hands-on portion of multiple data tables in the ecosystem, flared a question in my mind. "Does the 'full outer' join prioritize null values from the secondary table?"

The key was the ID values, yet when each table has null values, the data grid displays them out of order. I followed the video's instructions primary table is the Pay rates, double click into the physical layer, and drag the Positions table. simple right, double click the vin diagram and observe the data grid table details change. image 1 represents following the instructions of the video and observing the full outer join.

The keys (ID values) are out of order? Pay rates table key values (5,6,7,8) with 7 having NULL values and Positions table key values (5,6,8,9) with 9 having NULL values. image 1 displays ID #9(secondary table) prioritized over ID #7(primary table). Due diligence search and Ai questions said that is not how it works.

"The appearance of Table B's NULL values ahead of Table A's NULL values in a full outer join is not due to favoritism but rather due to how the join processes and the default sorting. By managing sorting and displaying settings, you can control the presentation of NULL values effectively" (OpenAI)

"Instead of relating the two tables at the logical level, you can join them using an outer join at the physical level, as in previous versions of Tableau. This approach will show the unmatched values, with a few side effects. Queries will always be issued querying both tables, NULL values will appear in visualizations and quick filters even when no fields from the unmatched table are used, and you will have to write LOD calculations to remove any unwanted duplication introduced by the join." What's Changed with Data Sources and Analysis - Tableau

From same source as above: "Nulls and automatic joins that result from relationships: In Tableau version 2020.2 and later, when performing joins that result from relationships, Tableau does not join nulls against nulls."

Whatever, I know what I see, plus we have yet to cover sorting data, apart from using the field name sorter... even that doesn't handle these NULL values correctly.

Try something else:

I tried Prioritizing (take it ease, I am new to this) the Pay rate table (w/ NULL value for ID #7) by making it the secondary table in the physical layer. Alright, by default the sort seems to be the ID field, yet with this new configuration it shows the ID values are numerically in order with NULL values.

As mentioned above I am new to this, I am constantly learning, and this is a learning point for me. If you have read this and could provide insight that would be greatly appreciated. Otherwise, I will continue to believe when working with NULL values, the default settings will always favor the secondary table upon performing full outer joins in the physical layer of Tableau Cloud.

For further reading and training, once my Coursera class advances to larger data sets is to practice the tutorials in this link. Relationships, part 2: Tips and Tricks (tableau.com)

Enjoy your weekend.

Tay

#DataScience #DataAnalysis #Tableau #DataIntegration #SQL #BusinessIntelligence #DataVisualization #BigData