PlanNode parent,
String selectorName,
String... columnNames ) {
PlanNode node = new PlanNode(Type.SOURCE, parent);
SelectorName selector = selector(selectorName);
node.addSelector(selector);
node.setProperty(Property.PROJECT_COLUMNS, columns(context, selector, columnNames));
node.setProperty(Property.PROJECT_COLUMN_TYPES, columnTypes(context, selector, columnNames));
return node;
}