休眠-一对一的n + 1个选择查询

Question

Organization is mapped to Address as 1-to-1:

Organization :

<one-to-one class="Address" constrained="true" name="address" property-ref="organizationId"/>

Address :

<many-to-one class="Organization"  name="organization">
          <column name="OrganizationID" not-null="false" unique="true"/>
  </many-to-one>

this query generates addtitional select for every Organization + 1:

   query = session.createQuery("select o from Organization as o where o.isCool=0").setReadOnly(true);
   organizations = query.list();

http://docs.jboss.org/hibernate/orm/3.3/reference/en/html/performance.html tells to fetch="join" but this doesn't make any difference. How to solve this problem? Any help is appreciated.

EDIT In debugger i can see that address is actually not lazy loaded, i have no idea why.

Answer 1

Since you are using an HQL to fetch your stuff, it would not help to simply use the annotation or the attribute that you are trying, to avoid the n+1 problem.

The right solution would be to make use of 'FETCH JOIN' clause in your query. You can follow the following link for more details: http://www.realsolve.co.uk/site/tech/hib-tip-pitfall.php?name=n1selects