Draft:Hub Star Modeling

Hub Star Modeling is a database modeling method specialized for data integration. It simplifies the integration of reference data, master data, and transactional data in data warehouses and data lakehouses. This method was introduced by Shahram Salami in 2024 [1]. Main Components Hub Star comprises two main components: hubs, which integrate entities from different data sources, and stars, which represent the data in relationships between these hubs.

Hubs Hubs are classified into three types: domain hubs, reference hubs, and virtual hubs, which represent master data, reference data, and transactional data:

•	Domain hubs abstractly define master data and transactional data by their business keys. •	Reference hubs define reference data with their business keys and descriptive attributes. •	Virtual hubs, including Time hub and Item hub, are not explicitly defined in the model but their keys are used in the star tables. The Time hub contains all timestamps, while the Item hub contains partial keys for week entities that lack independent business keys.

The following table represents the structure of domain and reference hubs:

Stars Stars represent the data in relationship between hubs. Depending on the implementation, stars are classified as either mutable or append-only stars. Some metadata are only supported in mutable stars. Stars have the following structure:

•	A minimal subset of hub keys, optionally combined with LoadTS, forms the star composite primary key. Modeling Example These ER diagrams represent a sample source schema and the target Hub Star model. Reference hubs are prefixed with ‘Ref’, and domain hubs are prefixed with ‘Dom’. The following table shows the entity mapping between the source and target models:

Hub Star Integration Matrix The Hub Star Integration Matrix facilitates the incremental development of the target model. It shows the participation of hubs in stars at the intersections of rows and columns. For example, the following table represents the integration matrix for the previous example. (The sign × indicates that the hub key is also part of the star primary key):