@Override
  public boolean checkAndCreateFlushedTimePartition(
      long timePartitionId, boolean usingDeviceFlushTime) {
    if (!partitionLatestFlushedTime.containsKey(timePartitionId)) {
      partitionLatestFlushedTime.put(
          timePartitionId,
          usingDeviceFlushTime
              ? new DeviceLastFlushTime()
              : new PartitionLastFlushTime(Long.MIN_VALUE));
      return false;
    }
    return true;
  }
record memory cost of map for each partitionId
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/HashLastFlushTimeMap.java