Index: cayenne-java/src/cayenne/java/org/apache/cayenne/access/DataDomainInsertBucket.java
===================================================================
--- cayenne-java/src/cayenne/java/org/apache/cayenne/access/DataDomainInsertBucket.java	(revision 603157)
+++ cayenne-java/src/cayenne/java/org/apache/cayenne/access/DataDomainInsertBucket.java	(working copy)
..-36,6 +36,7 @@
 import org.apache.cayenne.map.EntitySorter;
 import org.apache.cayenne.map.ObjAttribute;
 import org.apache.cayenne.map.ObjEntity;
+import org.apache.cayenne.map.ObjRelationship;
 import org.apache.cayenne.query.InsertBatchQuery;
 
 /**
..-145,6 +146,35 @@
                     idMap.put(dbAttrName, object.readPropertyDirectly(objAttr.getName()));
                     continue;
                 }
+                
+                // handle PKs behind to-one relationships
+                boolean found = false;
+                for (Iterator relIter = dbEntity.getRelationships().iterator(); relIter
+                        .hasNext();) {
+                    DbRelationship relationship = (DbRelationship) relIter.next();
+                    if (relationship.isToMany())
+                        continue;
+                    for (Iterator joinIter = relationship.getJoins().iterator(); joinIter
+                            .hasNext();) {
+                        DbJoin join = (DbJoin) joinIter.next();
+                        if (join.getSourceName().equals(dbAttrName)) {
+                            ObjRelationship objRel = objEntity
+                                    .getRelationshipForDbRelationship(relationship);
+                            DataObject target = (DataObject) object.readProperty(objRel
+                                    .getName());
+                            idMap.put(dbAttrName, target
+                                    .getObjectId()
+                                    .getIdSnapshot()
+                                    .get(join.getTargetName()));
+                            found = true;
+                            break;
+                        }
+                    }
+                    if (found)
+                        break;
+                }
+                if (found)
+                    continue;
 
                 // only a single key can be generated from DB... if this is done already
                 // in this loop, we must bail out.