Simple Query: Control output entities\structures
Aggregates & Queries
OutSystems 9
In my opinion Simple Query lacks the opion to choose if each entity/structure is part of the ouput or not. Something like the Advance Query.
It could be a simple flag property on each entity, where we would say if that entity will or not be part of the ouput or if it just used to join the tables.

Sometimes we need to make a query, joining multiple tables, but we just want to output one of the entities. This would save the need to create custom structures or "mixed" record lists.
Agreed. It won't often be a problem, but on occasion I've found myself writing an Advanced Query for just this reason.
Supposedly, the optimizer will output only the entities and attributes used in your flow.

Remaining attributes will be selected as NULL to fill the entity/structure (e.g. SELECT {USER}.[Id], NULL, NULL, NULL, ... FROM {USER} ...)

Nevertheless, it would be better not to have those dummy attributes selected at all...