Description Thorsten Ruth 2011-01-25 02:07:20 EST

Build Identifier: 20100617-1415

Assume an entity class A which contained an aggregate set of class B.

Classes:

class A {
    private Set<B> bees;

    public Set<B> getBees() {
		List<B> bList = new ArrayList<B>(bees);     //
		Collections.reverse(bList);                 // <- useless, but pictures the error
		return new HashSet<B>(bList);
    }

    public void setNicknames(final Set<B> bees) {
        this.bees = bees;
    }
}

class B {
    ...
}

orm.xml:

<entity-mappings>
	<entity class="A" access="PROPERTY">
		<table name="A"></table>
		<attributes>
			<element-collection name="bees" target-class="B">
				<collection-table name="B">
					<join-column name="a" />
				</collection-table>
			</element-collection>
		</attributes>
	</entity>
	<embeddable class="B">
		<attributes>
            ...
		</attributes>
	</embeddable>
</entity-mappings>

Test-Run:

entityManager.getTransaction().begin();
Query query = entityManager.createQuery("SELECT a FROM A a");
A a = query.getSingleResult();
entityManager.getTransaction().commit();


Enable full query logging (ALL) and you will see UpdateObjectQuerys for every element in Set<B>. This shouldn't happen, because nothing has changed.
Since sets have no explicid order, the set bees and its reversed version (see the getter of bee) have to be equal in mathematical sense.

After we debugging this issue, we found where the invalid set comparison take place. This comparison is valid for ordered collections but not for unordered collections.

org.eclipse.persistence.mappings.AggregateCollectionMapping.compareForChange(Object clone, Object backUp, ObjectChangeSet owner, AbstractSession session):
...
            while (cp.hasNext(cloneIterator)) {
                Object cloneObject = cp.next(cloneIterator, session);

                // For CR#2285 assume that if null is added the collection has changed.
                if (cloneObject == null) {
                    change = true;
                    break;
                }
                Object backUpObject = null;
                if (cp.hasNext(backUpIterator)) {
                    backUpObject = cp.next(backUpIterator, session);
                } else {
                    change = true;
                    break;
                }
                if (cloneObject.getClass().equals(backUpObject.getClass())) {
...



Reproducible: Always