@Override
  public long getUpdateTime() {
    if (lastTotalPointsNum != totalPointsNum) {
      lastTotalPointsNum = totalPointsNum;
      updateTime = System.currentTimeMillis();
    }
    return updateTime;
  }
Check whether updated since last get method
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/memtable/AbstractMemTable.java