Proposal: Add Hierarchy Support to the OSI Semantic Model Specification

[ki-kyvos]

Proposal: Add Hierarchy Support to the OSI Semantic Model Specification

I’d like to propose adding Hierarchies as a first-class construct within the OSI semantic model specification.

Hierarchies are a fundamental aspect of semantic layers and are widely used to organize dimensions into intuitive business navigation paths and enable richer analytical experiences.

Today, semantic models often expose dimensions as a flat collection of fields. While this provides interoperability at the attribute level, it misses an important layer of business semantics that many BI and analytics platforms rely upon.

Why hierarchies matter

Hierarchies provide meaningful organization of related attributes into business concepts that users naturally understand.

Examples:

Geography Hierarchy

Country
└── State
└── City

Time Hierarchy

Year
└── Quarter
└── Month
└── Day

Organization Hierarchy

Region
└── Business Unit
└── Department

Product Hierarchy

Category
└── Subcategory
└── Product

Benefits of adding hierarchy support to OSI

1. Preserve business semantics during interchange

Without hierarchy definitions, semantic model interchange loses valuable contextual information and requires downstream systems to reconstruct business relationships manually.

2. Improve interoperability across semantic platforms

Many semantic technologies already support hierarchies, either explicitly or implicitly. Standardizing hierarchy definitions would improve portability across vendors and reduce migration effort.

3. Better AI and agent experiences

AI agents benefit significantly from understanding hierarchical relationships.

For example, an agent can infer that:

• City rolls up to State
• State rolls up to Country
• Month rolls up to Quarter

This enables more accurate reasoning, drill paths, summarization, and question interpretation.

4. Consistent analytical navigation

Hierarchies define natural drill-down and roll-up paths that users expect across BI tools.

Examples:

• Sales by Country → State → City
• Revenue by Year → Quarter → Month
• Inventory by Category → Subcategory → Product

Potential OSI representation

Conceptually, hierarchies could be defined independently of dimensions and reference existing fields.

Example:

hierarchies:

• name: Geography
  levels:
  • country
  • state
  • city
• name: Time
  levels:
  • year
  • quarter
  • month
  • day

Additional metadata could optionally be supported in the future, such as:

• Parent-child hierarchies
• Ragged hierarchies
• User-defined display order
• Default drill paths

I would be interested in hearing the community’s thoughts on whether hierarchy support should become a first-class component of the OSI semantic model specification.

[krantikumarb]

I agree that we need hierarchy support in the OSI Semantic Model Specification, but we should brainstorm further on how and where to incorporate it.

[ki-kyvos]

Thanks @kranti. Happy to chat or meet. Does Monday 1PM IST work for you ?