clusterService, settings, transportActionProvider, symbolVisitor, mergeNode);
final AtomicInteger countdown = new AtomicInteger(upstreamResults.size());
final UUID operationId = UUID.randomUUID();
statsTables.operationStarted(operationId, mergeNode.contextId(), mergeNode.id());
Futures.addCallback(mergeOperation.result(), new FutureCallback<Object[][]>() {
@Override
public void onSuccess(@Nullable Object[][] rows) {
statsTables.operationFinished(operationId, null);
result.set(new QueryResult(rows));
}