NonUniqueObjectException migrating to hilo generator strategy

Question

I have a database with existing data, where previously I've been using AUTO_INCREMENT on the db to generate the PK.

To improve performance and facilitate bulk inserts, I'm trying to introduce a different key generation strategy:

public class BaseEntity implements Serializable  {

@Id
@GeneratedValue(generator="generator")
@GenericGenerator(
        name="generator", strategy="hilo")
private Integer id;

I've found documentation on the @GenericGenerator syntax hard to come by, so I'm not sure if I've implemented it correctly. As I understand it, this generator generate a PK for the entity PRIOR to performing the INSERT, therefore preventing the need for a post-insert query to discover the pk.

However, it's resulting in a org.hibernate.NonUniqueObjectException exception when trying to do an INSERT - presumably because the values hibernate is attempting to use for the PK's are already taken.

Is my understanding here correct, and - if so - how do I configure Hibernate to read the appropriate tables on startup and select the lower PK bounds?

Answer 1

It seems you are using tablehilo. Anyways, the Generator code is very important to troubleshoot the thing. So, please provide the relevant snippet.

Furthermore, I strongly suggest you to have a look at this approach here, if you have not already had.