// PERF: Avoid synchronized enumerator as is concurrency bottleneck.
Vector mappings = descriptor.getMappings();
int size = mappings.size();
for (int index = 0; index < size; index++) {
DatabaseMapping mapping = (DatabaseMapping)mappings.get(index);
changes.addChange(mapping.compareForChange(clone, null, changes, session));
}
}
// The following code deals with reads that force changes to the flag associated with optimistic locking.
if ((descriptor.usesOptimisticLocking()) && (changes.getPrimaryKeys() != null)) {