Hibernate version: 3.1.3 AND Ehcahe 1.2

Name and version of the database you are using: MS SQL Server 2000

I have a problem with one-to-one mapping. The way I use one-to-one mapping is by using a one-to-one on the parent side and a many-to-one reference on the child side. The problem I face is that while caching the parent entity, the child entity cannot be retrieved from a cache and a query is fired to fetch the child entity inspite of the child entity being cached. I understand that child objects can be retrieved from cache using primary key only, and the parent and child are not related using a primary key because of the one-to-one mapping limitation.

Mapping documents:
Snippets of mapping files are here:

The parent entity is Destination.
<hibernate-mapping
auto-import="true"
default-lazy="true">
<class
name="com.kuldip.search.data.Destination"
table="DESTINATION">
<cache usage="read-only" />
<id name="destinationId">
<column name="DestinationID" />
<generator class="native"></generator>
</id>
...............
<one-to-one
name="alternativePropertyDestination"
class="com.kuldip.domain.alternatives.AlternativePropertyDestination"
property-ref="destination"
fetch="join">
</one-to-one>
</class>
</hibernate-mapping>

The child entity is AltenativePropertyDestination:
<hibernate-mapping
auto-import="true"
default-cascade="none"
default-lazy="true">
<class
name="com.kuldip.domain.alternatives.AlternativePropertyDestination"
table="ALTERNATIVE_PROPERTIES_DESTINATION"
dynamic-insert="true"
dynamic-update="true">
<cache usage="read-only" />
<id
name="id"
type="long"
unsaved-value="null">
<column
name="ID"
sql-type="NUMBER(10)" />
<generator class="native"></generator>
</id>
<many-to-one
name="destination"
column="destinationId"
not-null="true">
</many-to-one>
<property
name="lastUpdated"
type="java.util.Date">
<column
name="LastUpdated"
not-null="true"
unique="false" />
</property>
</class>
</hibernate-mapping>

In the child entity I cannot use destination as the <id> because one-to-one mapping does not support it.

Every time I fetch the parent entity from cache a query is fired to fetch the child entity. This is affecting the performance. Is there any better way to tune one-to-one mapping?

Check out http://www.hibernate.org/162.html
Try having a constrained="true" on the one-to-one side indicating that there would always be a associated object for the one-to-one mapping. Hibernate will then provide a proxy for you in this case.