A single type of data store can hardly fulfill every end-user requirements in the NoSQL world. Therefore, polyglot systems use different types of NoSQL datastores in combination. However, the heterogeneity of the data storage models makes managing the metadata a complex task in such systems, with only a handful of research carried out to address this. In this paper, we propose a hypergraph-based approach for representing the catalog of metadata in a polyglot system. Taking an existing common programming interface to NoSQL systems, we extend and formalize it as hypergraphs. Then, we define design constraints and query transformation rules for three representative data store types. Next, we propose a simple query rewriting algorithm from the metadata of the catalog to underlying data store specific ones and provide a prototype implementation. Furthermore, we introduce a storage statistics estimator on the underlying data stores. Finally, we show the feasibility of our approach on a use case of an existing polyglot system, and its usefulness in metadata and physical query path calculations.

单一类型的数据存储几乎无法满足NoSQL世界中的所有最终用户要求。因此，多语言系统结合使用不同类型的NoSQL数据存储。但是，数据存储模型的异质性使得管理元数据成为此类系统中的一项复杂任务，仅进行了一些研究来解决这个问题。在本文中，我们提出了一种基于超图的方法来表示多声系统中的元数据目录。采用现有的NoSQL系统通用编程接口，我们将其扩展和形式化为超图。然后，我们为三种代表性的数据存储类型定义设计约束和查询转换规则。接下来，我们提出了一种简单的查询重写算法，从目录的元数据到基础数据存储特定的查询重写算法，并提供了原型实现。此外，我们在基础数据存储上引入了存储统计估算器。最后，我们展示了我们的方法在现有多语言系统的用例上的可行性，以及它在元数据和物理查询路径计算中的有用性。