Medallion Architecture: Why You Need It and How To Implement It With ClickHouse

In today’s fast-paced, data-driven world, businesses aren’t struggling with a lack of data—they’re drowning in it. The challenge lies in managing, processing, and extracting value from this massive influx of information. Without a clear structure, data pipelines become tangled, unreliable, and hard to scale.

This is where medallion architecture steps in.

Originally popularized in the context of modern data lakehouses, medallion architecture provides a structured, layered approach to managing data. When combined with high-performance databases like ClickHouse, it offers a scalable solution for real-time analytics.

In this article, we’ll cover:

• Understanding the medallion architecture and its importance.
• The advantages of using this framework in modern data systems.
• A hands-on demonstration of its implementation using ClickHouse.

What Is Medallion Architecture?

Medallion architecture is a layered framework designed to structure data pipelines efficiently. It organizes data into three progressive layers—Bronze, Silver, and Gold—each serving a specific purpose in the data processing lifecycle.

The Three Layers Explained:

1. Bronze Layer (Raw Data):

• Accepts raw data from diverse origins, including logs, APIs, and IoT devices.
• Prioritizes fast, scalable data ingestion with minimal transformation.

2. Silver Layer (Cleaned & Enriched Data):

• Cleans, filters, and enriches raw data to create a more structured and consistent dataset.
• Handles tasks like deduplication, schema validation, and joins with reference data.

3. Gold Layer (Business-Ready Data):

• Cleaned and structured data tailored for business intelligence (BI), reporting dashboards, and in-depth analytics.
• Aggregated metrics and KPIs are computed for fast, real-time queries.

Why Do We Need Medallion Architecture?

In traditional ETL (Extract, Transform, Load) pipelines, data transformations often happen in one monolithic process. This leads to:

• Complex, hard-to-maintain pipelines
• Difficult debugging when errors occur
• Inconsistent data across different teams

Medallion architecture solves these challenges by introducing clear, modular stages for data processing.

Key Benefits:

• Improved Data Quality: Each layer validates and cleans data progressively.
• Scalability: Handles large datasets by distributing transformations across layers.
• Flexibility: Teams have the freedom to interact with whichever data layer best fits their use case.
• Simplified Debugging: Issues can be traced back through specific layers, making troubleshooting easier.

How Medallion Architecture Works (With ClickHouse Example)

While medallion architecture can be implemented with various data platforms, ClickHouse—a high-performance, columnar database—offers unique advantages for real-time analytics.

Why ClickHouse?

• Blazing-fast query performance for large datasets
• Efficient data compression reduces storage costs
• Real-time ingestion capabilities for streaming data
• Flexible SQL support for complex transformations

Let’s walk through an example of how to implement medallion architecture using ClickHouse.

1. Bronze Layer: Raw Data Ingestion

The Bronze layer captures unrefined data directly from multiple sources. The goal is to ingest data as quickly and efficiently as possible, without worrying about quality or structure.

Example: Ingesting Raw Event Data

CREATE TABLE bronze_events (
    event_time DateTime,
    user_id UInt32,
    raw_data String
) ENGINE = MergeTree()
ORDER BY event_time;

Here, we’re simply capturing raw event logs (e.g., user clicks, server logs) in ClickHouse. The data may be messy, incomplete, or inconsistent—but that’s okay. The goal here is speed and reliability of data ingestion.

2. Silver Layer: Data Cleaning and Enrichment

In the Silver layer, raw data is cleaned and structured to ensure accuracy and usability. This includes:

• Parsing raw data (e.g., JSON fields)
• Filtering out invalid records
• Enriching with additional metadata

Example: Cleaning and Structuring the Data

CREATE TABLE silver_events (
    event_time DateTime,
    user_id UInt32,
    event_type String,
    event_value Float32
) ENGINE = MergeTree()
ORDER BY event_time;

INSERT INTO silver_events
SELECT 
    event_time,
    user_id,
    JSONExtractString(raw_data, 'event_type') AS event_type,
    toFloat32OrZero(JSONExtractString(raw_data, 'event_value')) AS event_value
FROM bronze_events
WHERE raw_data IS NOT NULL;

Now, the data is clean, structured, and enriched—making it easier for downstream analytics.

3. Gold Layer: Business-Ready Data

The Gold layer contains curated data, optimized for BI tools, dashboards, and business reporting. This data is often:

• Aggregated (e.g., daily sales, user activity metrics)
• Aligned with business KPIs
• Optimized for performance

Example: Aggregating Data for Business Insights

CREATE TABLE gold_daily_metrics (
    date Date,
    event_type String,
    total_value Float64
) ENGINE = MergeTree()
ORDER BY date;

INSERT INTO gold_daily_metrics
SELECT 
    toDate(event_time) AS date,
    event_type,
    SUM(event_value) AS total_value
FROM silver_events
GROUP BY date, event_type;

At this stage, the data is ready for consumption by business users, data analysts, and reporting tools like Grafana, Tableau, or Metabase.

Real-World Example: E-Commerce Analytics Pipeline

Imagine you’re running an e-commerce platform. Here’s how medallion architecture could be applied:

1. Bronze Layer: Ingest raw events such as page views, cart additions, purchases, and payment logs.
2. Silver Layer: Clean the data to identify valid transactions, remove duplicates, and enrich with product information.
3. Gold Layer: Aggregate daily revenue, conversion rates, and top-selling products for real-time business dashboards.

Why ClickHouse Is Perfect for Medallion Architecture

While medallion architecture can be implemented with other data platforms, ClickHouse excels for several reasons:

1. Blazing-Fast Query Performance: ClickHouse’s columnar storage allows for lightning-fast queries, especially when aggregating data in the Gold layer.
2. Real-Time Data Ingestion: Handles millions of events per second without breaking a sweat—ideal for the Bronze layer.
3. Efficient Data Compression: Reduces storage costs through advanced compression algorithms, making it cost-effective to store raw data long-term.
4. Powerful SQL Support: Offers flexible SQL capabilities for complex transformations, joining datasets, and aggregations across all layers.

Common Challenges (and How to Overcome Them)

1. Data Duplication: Use ClickHouse’s deduplication features and versioning to ensure data consistency.
2. Schema Evolution: Leverage ClickHouse’s flexible schema handling for dynamic data structures without downtime.

3. Complex Joins: Optimize joins with pre-aggregated data in the Silver layer to improve query performance.

When Should You Use Medallion Architecture?

Medallion architecture is ideal for:

• Real-Time Analytics Platforms: Monitoring user activity, IoT devices, etc.
• Data Warehousing: Managing large datasets for reporting and BI tools.
• Event-Driven Architectures: Processing clickstream data, server logs, and telemetry.

Final Thoughts

The medallion architecture isn’t just a theoretical concept—it’s a proven framework that helps organizations manage their data pipelines more effectively. By structuring data into Bronze, Silver, and Gold layers, you can:

• Improve data quality
• Enhance scalability
• Simplify data transformations

When paired with ClickHouse, you get a high-performance, scalable solution that can handle real-time analytics with ease.

If you found this article helpful, share your thoughts in the comments. How are you managing data pipelines in your organization?