@Override
  public void setAlias(IMeasurementMNode<IConfigMNode> measurementMNode, String alias) {
    String existingAlias = measurementMNode.getAlias();
    if (existingAlias == null && alias == null) {
      return;
    }
    measurementMNode.setAlias(alias);
  }
This is a memory-based implementation of IMTreeStore. All MNodes are stored in memory.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/persistence/schema/ConfigMTreeStore.java