8.1 — What Are Semantic Models?

Semantic models are the brain of Power BI. They sit between raw data and dashboards — translating tables into business logic.

They define:

• Measures
• Relationships
• Hierarchies
• Aggregations
• RLS / OLS
• Calculation groups
• Metadata

Without a semantic model, raw data is just tables. With one, it becomes a governed, reusable analytics layer that every dashboard in the organization can build on.

Direct Lake — The Biggest Innovation in Power BI’s History

For years, Power BI was stuck between two modes:

• Import Mode — fast, reliable, but required scheduled refresh cycles
• DirectQuery Mode — real‑time, but slow and limited

Direct Lake eliminates the tradeoff entirely. Semantic models read Delta tables directly from OneLake — no refresh, no duplication, no latency.

Benefits:

• No refresh cycles
• No data duplication
• Real‑time dashboards
• Lower storage cost
• High performance (Import-class speed)
• No incremental refresh logic
• No scheduled jobs

Direct Lake is the clear winner for enterprise BI. It combines the speed of Import with the freshness of DirectQuery — and adds the governance of OneLake on top.