The diagram that you see in the data panel for Tableau desktop is the Data Model
What type of joins you create, how many tables you bring in for your analysis will have an impact on performance of your dashboards
In general the more tables you have, the more your database has to do. So, less is better.
The best practices I follow for Data Model are:
- try to limit the number of data tables to be < 5. In the example above, we are using 4 tables
- Inner joins are always better for performance than outer or left/right joins. Having said that, you don’t get to decide the join type based on performance, you have to decide the join type based on the use case