private void appendOneSelectedRow(List<List<Integer>> selectedRowIndexArray) {
    for (int i = 0; i < inputOperatorsCount; i++) {
      selectedRowIndexArray.get(i).add(inputIndex[i] - 1);
    }
  }
Indicate whether we found an empty child input in one loop
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/process/join/InnerTimeJoinOperator.java