1. Upload a module (from default template): ```rust #[table(name=person)] pub struct Person { #[primary_key] name: String, } ``` 2. Remove the `#[primary_key]` column annotation and upload again (successfully): ```rust ▸ Removed index person_name_idx_btree on [name] of table person ▸ Removed unique constraint person_name_key on [name] of table person ``` 4. Change absolutely anything in the module (incl. in a reducer body) and upload. Result: ```error Publishing module... Error: Failed to create or update the database: Primary key mismatch: expected self.primary_key == def.primary_key: self.primary_key: Some(ColId(0)) def.primary_key: None ```