I need to generate unique identifiers programmatically. They aren't supposed to be primary keys they simply must be unique within the scope of the database. I am planning on storing them in a long value and using them as customer reference numbers. I cannot and do not want to use primary keys for that purpose because the reference numbers have a business meaning and they may be repeated in some of the tables.

How do I use the Hibernate API to generate myself a unique id, preferably using a method native to the underlying database? Thanks for your answer and apologies if it's already covered somwhere. A search that I did on the site showed no useful results

You can generate ids on multiple ways: http://www.hibernate.org/hib_docs/reference/html/or-mapping.html#or-mapping-s1-4--generator

You can not map propertys that are generated by Hibernate, you need to do that manually.

Do it yourself (session.connection()) and have a look at the n.s.h.id pachake sources.