private int getColumnIndex(Symbol symbol, PlanNode node) {
    String name = symbol.getName();
    int channel = 0;
    for (Symbol columnName : node.getOutputSymbols()) {
      if (columnName.getName().equals(name)) {
        return channel;
      }
      channel++;
    }
    throw new IllegalStateException(
        String.format("Found no column %s in %s", symbol, node.getOutputSymbols()));
  }
This Visitor is responsible for transferring Table PlanNode Tree to Table Operator Tree.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/TableOperatorGenerator.java