Deferrable Foreign Key Constraints
Deferrable constraints are usually wrong. It's a proof that your ORM does something wrong. Usual problems are


commit might fail. This is usally not expexted by various tools and also by developers
commit might last very long. This might be problem with distributed(XA) transactions.
also troubleshooting might be problematic, especially when using Java(JDBC). When commit fails you can hardly say which particular constraint failed the transaction