Property graphs often contain tree-shaped substructures, yet they are not captured by existing proposals for graph schemas; likewise, query languages and query engines offer little-to-no native support for managing them systematically. As a first contribution, we report on a micro experiment that demonstrates the optimization potential of treating tree-shaped substructures as first class citizens in graph database systems. In particular, we show that in systems backed by relational engines, we can achieve substantial speedups by leveraging structural indexes, as originally developed for XML databases, to accelerate path queries. Based on our findings, we put forward a vision in which tree-shaped substructures are systematically managed throughout the graph query lifecycle, from modeling and schema design to indexing and query processing, and outline arising research questions.

翻译：属性图常包含树形子结构，但现有图模式方案未能有效捕捉此类结构；同样，查询语言与查询引擎也几乎未提供系统性管理树形子结构的原生支持。作为第一项贡献，我们通过微观实验论证了将树形子结构作为一等公民处理在图数据库系统中的优化潜力。具体而言，我们证明在基于关系引擎的系统中，通过利用最初为XML数据库开发的结构化索引来加速路径查询，可获得显著的性能提升。基于这些发现，我们提出一种系统性管理树形子结构的愿景，涵盖从建模与模式设计到索引与查询处理的整个图查询生命周期，并阐述了由此产生的研究问题。