lazy="true" ignored on many-to-many

cbredesen · **Posted:** Tue Jun 20, 2006 12:08 pm

All,

Please consider the following scenario which I'm implementing using Hibernate 3.0.5 on Oracle 10g:

Code:

<class name="Merchant" table="MERCHANT" lazy="false">
   <cache usage="read-write"/>
   <set name="warehouseAddresses" table="LINKMERCHANTADDRESS" lazy="true" cascade="none"  sort="unsorted">
      <key column="MERCHANTID" foreign-key="LMA_MERCHANTID_FK"></key>
      <many-to-many class="com.comerxia.core.model.Address" column="ADDRESSID" outer-join="auto" foreign-key="LMA_ADDRESSID_FK"/>
   </set>
</class>

Code:

<class name="Address" table="ADDRESS" lazy="true" discriminator-value="null">
   <subclass name="com.comerxia.core.model.WarehouseAddress" lazy="true" discriminator-value="WAREHOUSE">
      <property name="code" type="java.lang.String" update="true" insert="true" column="CODE" unique="true"/>
   </subclass>
</class>

Notice that Merchant has a Set (many-to-many) of Addresses. Merchant is not lazy, but the set is intended to be. Address does have a polymorphically mapped subclass, WarehouseAddress.

When I load a Merchant, the set of Addresses is fetched eagerly using a select (N+1, in fact). No matter what I do (played with lazy/!lazy, etc.), I cannot get the many-to-many to lazy-load.

I am convinced that this is something I'm doing wrong, but I can't find the explanation in the docs, nor can I come up with a scnenario that causes the lazy="true" declaration to be obeyed. Debug level logging during the fetch of Merchant reveals that Hibernate is classifying this as a non-lazy collection. The Set is actually PersistentSet at runtime, and the populated Address beans are actually proxies. So the system is providing me with the correct implementations, but it is initializing the set prematurely. If I make Merchant lazy="true", the whole Set is initialized with the first call to any Merchant property.

I'm going to attack this by (correctly, I think), unmapping the set from Merchant and simply querying for the Addresses when I need them, but I still don't have the answer as to why this isn't working for me.

Any ideas?

-Chris

TheXFed · **Posted:** Wed Jul 26, 2006 9:47 pm

I also came across the exact same problem recently. No matter what it seemed like a many-to-many couldn't be eagerly fetched.

However, I ended up fixing the probem for myself, so perhaps this will help you (if you haven't already solved it). try setting lazy="false" and outer-join="true" on the side you want eagerly fetched.

cbredesen · **Posted:** Thu Jul 27, 2006 2:24 pm

Actually what I wanted was the opposite - lazy loading of the Set that is deferred until it is accessed. Everything looked right except the Set was loaded right after the owner even if I didn't iterate over it. I never did solve it, so I wound up creating an extra entity and removing the mapped collection from its owner.

Thanks anyway,

Chris