public int getColumnCount(int index) {
    if (index == internalTVList.size() - 1) {
      SerializableTVList lastList = internalTVList.get(index);
      return lastList.getColumnCount();
    } else {
      return internalColumnCountList.get(index);
    }
  }
Set the upper bound.

@param evictionUpperBound the index of the first element that cannot be evicted. in other
    words, elements whose index are <b>less than</b> the evictionUpperBound can be evicted.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/transformation/datastructure/tv/ElasticSerializableTVList.java