Menu
After migrating to Hibernate 5.2.7, I seem to be getting incorrect values for the id field.
My code:
@Id @SearchableId
@GeneratedValue(strategy=GenerationType.AUTO, generator="hms_seq_gen")
@SequenceGenerator(name="hms_seq_gen", sequenceName="patregn_seq")
protected Integer ID;
Hibernate fires this query:
select nextval ('patregn_seq')
which gives 5367. The last value in the id field in the table is 5358.
And I get this ERROR: duplicate key value violates unique constraint "patientregistration_pkey"
[java] Detail: Key (id)=(5318) already exists.
I am sure this question is similar to this and this, but I am forced to ask because the solution given there does not work for me:
I added
<property value="true" name="hibernate.id.new_generator_mappings"/>
to my persistence.xml, but to no avail. Any help would be greatly appreciated.
200
To avoid this performance penalty (and make the SEQUENCE generator even worth using), Hibernate utilises an optimization where it assumes that it can allocate itself blocks of IDs from the sequence.
Before Hibernate performs any inserts of an entity, it will query the database to receive the next value in the identifier sequence. It can then use that value as the ID of the following insert. In terms of SQL, it would look like this:
By default, Hibernate will try to work off of a single sequence called hibernate_sequence, so to use the default behaviour, we should create this sequence before running our application (maybe in a migration). This is not too bad and works out of the box.
This entire strategy relies on the backing database sequence incrementing in line with Hibernate's expectations. If we have a mismatch and the database sequence increments only by 1, whilst Hibernate expects it to increment by 50, the following happens if we restart the application:
Actually when you migrate to the new Hibernate version 5.2.7, hibernate.id.new_generator_mappings defaults to true.
For backward compatibility you should change this flag to false.
For more information please search the userguide for new_generator_mappings: - http://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html
61
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
