Hibernate and Postgresql - generator class in hibernate mapping file

The ids in my postgresql database are auto-incremental (there are sequences defined in a database). When creating a hibernate mapping files I set the class generator to increment:

<class name="model.Names" schema="public" table="names">
    <id name="id" type="int">
      <column name="id"/>
      <generator class="increment"/>
    </id>

However, I keep getting all kinds of errors (null pointer exceptions, org.hibernate.TransactionException: Transaction not successfully started) so I first wanted to make sure that this is the right generator class before debugging and looking for errors elsewhere. I tried sequence (does not work at all, the increment works in some cases). The application is written in JSF 2.0.

Thanks in advance for any suggestions.

Best Regards, sass.

Solution

If you want to use sequences, you should definitely use one of the sequence or seqhilo if you want a hi/lo algorithm generators. The problem is that "does not work at all" does not help at all to understand what problem you faced.

Just in case, here is a snippet for the sequence generator:

<id name="id" type="long" column="person_id">
        <generator class="sequence">
                <param name="sequence">person_id_sequence</param>
        </generator>
</id>

And for the seqhilo generator:

<id name="id" type="long" column="cat_id">
        <generator class="seqhilo">
                <param name="sequence">hi_value</param>
                <param name="max_lo">100</param>
        </generator>
</id>

If you want to investigate why it "does not work at all", I suggest to enable logging of the generated SQL to see what is happening.

Also note that PostgreSQL does support the identity generator (see HB-875 and HHH-1675) when using SERIAL or BIGSERIAL columns.

References

Hibernate Core Reference Guide