Indicates that the persistence provider must assign primary keys for the entity using an underlying database table to ensure uniqueness.

Indicates that the persistence provider must assign primary keys for the entity using a database sequence.

Indicates that the persistence provider must assign primary keys for the entity using a database identity column.

Indicates that the persistence provider should pick an appropriate strategy for the particular database. The AUTO generation strategy may expect a database resource to exist, or it may attempt to create one. A vendor may provide documentation on how to create such resources in the event that it does not support schema generation or cannot create the schema resource at runtime.