public void setTreeColumnToTsBlockIndexMap(List<String> outputColumnNames) {
    this.columnToTsBlockIndexMap = new HashMap<>(outputColumnNames.size());
    for (int i = 0; i < outputColumnNames.size(); i++) {
      columnToTsBlockIndexMap.put(outputColumnNames.get(i), i);
    }

    this.columnIndex2TsBlockColumnIndexList = new ArrayList<>(columnHeaders.size());
    for (ColumnHeader columnHeader : columnHeaders) {
      columnIndex2TsBlockColumnIndexList.add(
          columnToTsBlockIndexMap.get(columnHeader.getColumnName()));
    }
  }
The header of query result dataset.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/common/header/DatasetHeader.java