Medallion Architecture: A complete Guide

The Medallion Architecture is a modern data organization pattern widely used in Data Warehouses, Data Lakes, and Lakehouses. Its goal is to structure data in progressive quality layers, facilitating governance, reprocessing, scalability, and analytical consumption.

This model was popularized by Databricks and today is considered an essential best practice in modern data architectures.

What is Medallion Architecture?

The Medallion Architecture organizes data into three main layers, where each layer represents a higher level of refinement and value:

• Bronze → raw data
• Silver → cleansed and trusted data
• Gold → business-ready data ready for consumption

Quick summary: data enters raw, gets cleaned, and is then transformed into business metrics.

Medallion Architecture Overview

Bronze Layer: Raw Data

What is the Bronze layer?

The Bronze layer stores data exactly as it arrives from the source, without significant transformations.

Bronze layer characteristics:

• Raw data
• Structure close to the source
• May contain errors and duplicates
• High volume
• Foundation for auditing and reprocessing

Goal: preserve the original data as the source of truth.

Silver Layer: Cleansed and Enriched Data

What is the Silver layer?

The Silver layer contains clean, standardized, and trusted data, ready for consistent analysis.

Common transformations:

• Deduplication
• Type casting and standardization
• Validation of required fields
• Enrichment through joins

Goal: ensure data quality and consistency.

Gold Layer: Business Layer

What is the Gold layer?

The Gold layer represents the final level of the Medallion Architecture. Here, the data is ready for business consumption.

Examples of Gold data:

• Monthly revenue
• Churn rate
• LTV
• Executive metrics

Goal: deliver direct value for decision-making.

How the Medallion Architecture Scales with Business Growth

One of the main differentiators of the Medallion Architecture is its ability to scale without requiring deep restructurings as the business evolves.

As new data sources emerge:

• They land directly into the Bronze layer
• They do not impact existing models in Silver or Gold
• They maintain isolation between ingestion and consumption

This decoupling allows data teams to evolve pipelines and business models incrementally, without disrupting reports or analytical products already in production.

Medallion Architecture and Evolving Business Rules

Business rules change constantly: metric definitions, segmentation criteria, financial calculations.

In the Medallion Architecture:

• The original data remains preserved in Bronze
• Silver ensures structural consistency
• Gold can be reprocessed whenever a rule changes

This eliminates a common issue in traditional Data Warehouses: recalculating metrics without losing history or causing inconsistencies.

The result is greater trust in the numbers and less reliance on manual fixes.

Governance and Observability in Medallion Architecture

The clear separation between Bronze, Silver, and Gold simplifies the implementation of data governance and observability.

Each layer can have:

• Distinct SLAs
• Specific quality rules
• Independent monitoring

Additionally, issues become localized:

• Ingestion errors → Bronze
• Quality issues → Silver
• Metric inconsistencies → Gold

This reduces troubleshooting time and improves the reliability of the data ecosystem.

Common Pitfalls When Implementing Medallion Architecture

Despite its conceptual simplicity, some mistakes are frequent:

• Applying business rules in Bronze
• Skipping the Silver layer to "move faster"
• Creating multiple definitions of metrics in Gold
• Not versioning transformations
• Treating the architecture merely as a naming convention

Avoiding these pitfalls is essential for the Medallion Architecture to deliver its expected benefits.

Benefits of the Medallion Architecture

• Better data quality
• Governance and lineage tracking
• Reliable reprocessing
• Scalability
• Clear separation of concerns

Best Practices in Medallion Architecture

• Do not apply business rules in Bronze
• Use columnar formats
• Version schemas per layer
• Monitor quality in Silver
• Document metrics in Gold

When to Use Medallion Architecture?

Use the Medallion Architecture when:

• There are multiple data sources
• Governance is critical
• Reprocessing is frequent
• The Data Warehouse has become a bottleneck
• BI and Analytics need to scale

FAQ – Medallion Architecture

What is Medallion Architecture?

It is a data organization pattern in layers (Bronze, Silver, and Gold) that improves quality and governance.

Are "Arquitetura Medalhão" and "Medallion Architecture" the same thing?

Yes. "Arquitetura Medalhão" is simply the Portuguese translation of Medallion Architecture.

Can I consume data directly from the Silver layer?

Yes. This is common for exploratory analysis and data science.

Conclusion

The Medallion Architecture is one of the most important design patterns for modern data architectures. By structuring data into progressive layers, it builds a reliable, scalable, and growth-ready environment.

If you are modernizing your Data Warehouse or building a Lakehouse, adopting the Medallion Architecture is an essential step.