Why would Spring's HibernateTemplate's loadAll() method generate updates for each row?

Question

I have a database table consisting of countries. In my DAO which extends HibernateDAOSupport the following method...

public List<Country> getCountries() {
 return getHibernateTemplate().loadAll(Country.class);
}

...generates the following activity:

Hibernate: update countries set name=?, iso_alpha_2=?, iso_alpha_3=? where id=?
Hibernate: update countries set name=?, iso_alpha_2=?, iso_alpha_3=? where id=?
Hibernate: update countries set name=?, iso_alpha_2=?, iso_alpha_3=? where id=?
...
once for each row

The method works, however. I get my list of countries, but what's with all the updates?

My mapping for this class isn't terribly exotic:

<class name="Country" table="countries">
 <id name="id" column="id">
  <generator class="identity"/>
 </id>
 <property name="name" column="name"/>
 <property name="alpha2" column="iso_alpha_2" />
 <property name="alpha3" column="iso_alpha_3" />
</class>

Can anyone point me in the right direction? Why would loadAll be triggering updates?

Answer 1

Hibernate apparently thinks that the values it loaded from the DB have changed, so it's flushing the updates.

You can just set 'mutable="false"' in the class mapping, which should stop the updates, but that's not ideal.

Try setting 'dynamic-update="true"' on the class mapping, and that will at least show which column Hibernate thinks needs updating. Are the values in the countries table actually being changed in any way? I think if you set debug logging on the org.hibernate.type package you'll also get debug output showing what values are being bound for the update statements.

This sort of effect can occur if the model object tries to be clever- e.g. trimming whitespace, making a change to the value that the database doesn't preserve.