private void clearTsBlockCache(Binary endTimeSeries) {
    for (int i = 0; i < inputOperatorsCount; i++) {
      if (!empty(i)
          && comparator.compare(
                  getTimeSeries(inputTsBlocks[i], inputTsBlocks[i].getPositionCount() - 1),
                  endTimeSeries)
              == 0) {
        inputTsBlocks[i] = null;
      }
    }
  }
If the tsBlock of columnIndex is null or has no more data in the tsBlock, return true; else
return false.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/process/last/LastQueryMergeOperator.java