public Long getDatabaseId(Object o)
	{
		Long res = null;
		WeakReference<Object> wref = objectToRef.get(o);
		if (wref != null)
		{
			TableEntry te = referenceToTable.get(wref);
			if (te != null)
			{
				res = te.getDbId();
			}
		}
		return res;
	}