Section 4 — OneLake Architecture — How It Actually Works

OneLake is built on ADLS Gen2, but Fabric adds several layers on top:

1. Delta Lake Storage Layer

All structured data is stored as Delta tables: ACID transactions, Schema evolution, Time travel, Partitioning, Z-Order, File compaction.

2. Fabric Namespace Layer

Every workspace becomes a folder in OneLake.

Example path: /OneLake/WorkspaceName/LakehouseName/Tables/Gold/Sales

3. Multi-Engine Access Layer

Spark, SQL, Power BI, ML, and Event Streams all read the same Delta files.

4. Governance Layer

Purview applies: Sensitivity labels, Lineage, Access control, Classification.

5. Shortcut Layer

OneLake can reference external data without copying it.

6. Security Layer

RBAC applies consistently across all workloads.

This architecture is what makes OneLake unified, governed, and scalable.

Section 5 — Shortcuts — The Most Underrated Feature of OneLake

Shortcuts allow OneLake to reference external data sources without copying the data.

Supported shortcut sources: ADLS, Amazon S3, Other OneLake workspaces.

Why Shortcuts Matter

• Zero duplication
• Zero ingestion cost
• Zero synchronization
• Zero refresh cycles
• Unified governance
• Unified security
• Unified lineage

Shortcuts turn OneLake into a virtualized global data lake.

Example Use Cases

• Reference S3 data from a Lakehouse
• Reference ADLS data from a Warehouse
• Reference another team’s Lakehouse without copying
• Build BI models on external data without ingestion

Shortcuts are the key to eliminating data silos.