private static void printFragmentNodes(
StringBuilder output, PlanFragment fragment, PlanNodeIdGenerator idGenerator) {
String clusterId = "cluster_" + fragment.getId();
output.append("subgraph ").append(clusterId).append(" {").append('\n');
output.append(format("label = \"%s\"", fragment.getPartitioning())).append('\n');
PlanNode plan = fragment.getRoot();
plan.accept(new NodePrinter(output, idGenerator), null);
output.append("}").append('\n');
}
