// PERF: Avoid synchronized enumerator as is concurrency bottleneck.
Vector mappings = descriptor.getMappings();
int mappingsSize = mappings.size();
for (int index = 0; index < mappingsSize; index++) {
DatabaseMapping mapping = (DatabaseMapping)mappings.get(index);
changes.addChange(mapping.compareForChange(clone, backUp, changes, session));
}
return changes;
}