@Override
public Void visitMergeNode(MergeNode node, Job context) {
node.contextId(context.id());
if (node.executionNodes().isEmpty()) {
context.addTask(new LocalMergeTask(
threadPool,
clusterService,
settings,
transportActionProvider,
new ImplementationSymbolVisitor(referenceResolver, functions, RowGranularity.CLUSTER),