@Override
  public IMNodeIterator<IMemMNode> getTraverserIterator(
      final IMemMNode parent,
      final Map<Integer, Template> templateMap,
      final boolean skipPreDeletedSchema)
      throws MetadataException {
    if (parent.isDevice()) {
      final AbstractTraverserIterator<IMemMNode> iterator =
          new MemoryTraverserIterator<>(this, parent.getAsDeviceMNode(), templateMap, nodeFactory);
      iterator.setSkipPreDeletedSchema(skipPreDeletedSchema);
      return iterator;
    } else {
      return getChildrenIterator(parent);
    }
  }
This is a memory-based implementation of IMTreeStore. All MNodes are stored in memory.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/impl/mem/MemMTreeStore.java