I get that there's a commercial agenda to shift reliance on writing SQL to using Tableau UI, but I don't think it's a fair argument to say that having nested logic at 18:59 would lead to performance issues. First of all, we must remember that the query is executed at every drag-and-drop you execute. The query on the left executes Tableau logic on the entire raw table. This can be managed by encoding WHERE filters in your custom SQL code so that you only work with the data you really need. While it is possible to perform these same filters on the data source step in Tableau, remember that every layer of logic you define on the UI is another heavy query.
