@Override
  protected void releaseNode(N node) {
    if (!node.isAboveDatabase() && !node.isDatabase()) {
      // In any case we can call store#inpin directly because the unpin method will not do anything
      // if it is an IMNode in template or in memory mode.
      store.unPin(node);
    }
  }
The interface to start the traversal. The node process should be defined before traversal by
overriding or implement concerned methods.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/mtree/traverser/Traverser.java