@Override
  public int estimateSize() {
    return 8 + 8 + databaseInfo.estimateSize() + basicMNode.estimateSize();
  }
The basic memory occupied by any AbstractDatabaseMNode object

<ol>
  <li>object header, 8B
  <li>node attributes
      <ol>
        <li>databaseInfo reference, 8B
        <li>basicMNode reference, 8B
      </ol>
  <li>MapEntry in parent
</ol>
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/schema/node/common/AbstractDatabaseMNode.java