public void declareKey(String keyFor, String ID, String type) {
        String name = ID;
        if (idName != null) {
            name = (String) idName.get(ID);
        }
        if (keyFor.equals("node")) {
            Column c = graph.getVertexTable().getColumn(name);
            if (c == null) {
                c = createColumn(type, name);
                graph.getVertexTable().addColumn(c);
            }
        }
        else if (keyFor.equals("edge")) {
            Column c = graph.getEdgeTable().getColumn(name);
            if (c == null) {
                c = createColumn(type, name);
                graph.getEdgeTable().addColumn(c);
            }
        }
    }