Graph database users today face a choice between two technology stacks: the Resource Description Framework (RDF), on one side, is a data model with built-in semantics that was originally developed by the W3C to exchange interconnected data on the Web; on the other side, Labeled Property Graphs (LPGs) are geared towards efficient graph processing and have strong roots in developer and engineering communities. The two models look at graphs from different abstraction layers (triples in RDF vs. edges connecting vertices with inlined properties in LPGs), expose - at least at the surface - distinct features, come with different query languages, and are embedded into their own software ecosystems. In this short paper, we introduce a novel unifying graph data model called Statement Graphs, which combines the traits of both RDF and LPG and achieves interoperability at different levels: it (a) provides the ability to manage RDF and LPG data as a single, interconnected graph, (b) supports querying over the integrated graph using any RDF or LPG query language, while (c) clearing the way for graph stack independent data exchange mechanisms and formats. We formalize our new model as directed acyclic graphs and sketch a system of bidirectional mappings between RDF, LPGs, and Statement Graphs. Our mappings implicitly define read query semantics for RDF and LPGs query languages over the unified data model, thus providing graph users with the flexibility to use the query language of their choice for their graph use cases. As a proof of concept for our ideas, we also present the 1G Playground; an in-memory DBMS built on the concepts of Statement Graphs, which facilitates storage of both RDF and LPG data, and allows for cross-model querying using both SPARQL and Gremlin.

翻译：图形数据库用户当前面临两种技术栈的选择：一方面，资源描述框架（RDF）是W3C最初为在Web上交换互联数据而开发的具有内置语义的数据模型；另一方面，标签属性图（LPG）面向高效图处理，并在开发者和工程社区中具有深厚根基。这两种模型从不同抽象层次审视图（RDF中的三元组 vs. LPG中连接内联属性顶点的边），至少在表面呈现出不同特性，支持不同查询语言，并嵌入各自的软件生态系统中。本文提出一种名为"声明图"的新型统一图数据模型，它融合了RDF和LPG的特征，并在不同层面实现互操作性：（a）提供将RDF和LPG数据作为单一互联图进行管理的能力，（b）支持使用任意RDF或LPG查询语言对集成图进行查询，同时（c）为独立于图栈的数据交换机制与格式铺平道路。我们将新模型形式化为有向无环图，并概要描述RDF、LPG与声明图之间的双向映射系统。该映射隐式定义了针对统一数据模型上RDF和LPG查询语言的读查询语义，从而为图用户提供灵活选择最适合其图应用场景的查询语言的能力。作为概念验证，我们还展示了1G Playground——一个基于声明图概念构建的内存数据库管理系统，支持存储RDF和LPG数据，并允许使用SPARQL和Gremlin进行跨模型查询。