Indicates that a many to one, one to one, or many to many association maps to a column holding foreign keys, but without a foreign key constraint, and which may therefore violate referential integrity.

The action specifies how Hibernate should handle violations of referential integrity, that is, the case of an orphaned foreign key with no associated row in the referenced table:

• NotFoundAction#EXCEPTION specifies that this situation should be treated as an error, causing a org.hibernate.exception.ConstraintViolationException, and
• NotFoundAction#IGNORE specifies that this situation should be tolerated and treated as if the foreign key were null.

Note that this annotation has the side effect of making a to-one association non-lazy. It does not affect the laziness of a many-to-many association.

This annotation implies jakarta.persistence.ConstraintMode#NO_CONSTRAINT for the purposes of DDL generation. That is, no foreign key constraint will be included in the generated DDL.