Cannot persist my model to database (M2)

Question

I have a custom model object and want to persist it to the related database table. When I try to save the model, nothing happens. In case I do not enter required fields, I get an "Integrity constraint violation" exception. The inner message shows me, that the model is working on the right table. Saving a model did work that way in other situations before. But ofter some changes I have the described problem. Does anyone know, why the model cannot be saved and no error is thrown?

Code:

public function createModelEntry(\vendor\Module\Api\Data\MyModelInterface $modelData) { $modelData->save(); }

Answer 1

Ok, it seems that magento does not support multi-column primary keys on its tables. That leads to the strange behaviour that the constraint validation works when saving a model but the saving itself fails without any error message. I have modified my table so it use only one primary key column.