<table-generator> and the resulting ID

revilo · **Joined:** Tue Feb 13, 2007 10:27 am **Posts:** 4

Hibernate version: 3.2.1GA

Mapping documents:

Code:

<table-generator name="rm_user" table="xa_sequences" pk-column-name="sequence_name" value-column-name="last_number" pk-column-value="rm_user" allocation-size="1"/>

<entity class="IDUser">
   <table name="rm_user" />
   <attributes>
   <id name="id">
       <column name="user_id" unique="true"/>
       <generated-value strategy="TABLE" generator="rm_user"/>
   </id>
</entity>

As far as I understand section 9.1.38 (TableGenerator Annotation) of the JPA spec, the column defined by value-column-name does contain the last value generated. I.e. if it contains 1, the next entity to be inserted into the database should get 2 as its ID.
The setup for our testcases populates the database with some entries, so we do have some entires in the table rm_user and a corresponding entry in the xa_sequences table with the column last_number set to MAX(rm_user.id). With org.hibernate.id.MultipleHiLoPerTableGenerator used as default ID generator, the next entity to be persisted is assigned the same value MAX(rm_user.id).
Is my intrepretation of the JPA spec incorrect or does the generator indeed return an erroneous value?

emmanuel · **Posted:** Thu Feb 15, 2007 7:52 pm

thing is when the allocationSize != 1 (default to 50), the max strategy doesn't apply anyway.

revilo · **Joined:** Tue Feb 13, 2007 10:27 am **Posts:** 4

emmanuel wrote:

thing is when the allocationSize != 1 (default to 50), the max strategy doesn't apply anyway.

As the allocationSize is set to 1, I do not get the connection...

Let me put it in another way:
- The column last_number contains 1, a user is already present in the db with id 1.
- The app is started, a new user is inserted.
- Hibernate will assign 1 as the next id, which leads to an exception; Toplink e.g. will assign 2 as the next id, which is IMHO as the spec states how it should be.