@Override
  public void moveDataToNewMNode(IDatabaseMNode<N> newMNode) {
    // Do nothing
  }
when the data file in a database is older than dataTTL, it is considered invalid and will be
eventually deleted. TODO: database ttl is useless here, which can be removed.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/impl/mem/mnode/info/DatabaseDeviceInfo.java