Stage 2 · Lesson 9 of 9

Medallion and layered architecture

Most platforms store data in , each cleaner than the one before. The medallion architecture, common on and , names them bronze, silver and gold. Bronze is raw data exactly as it arrived.

Silver is cleaned: correct types, no duplicates, consistent names. Gold is ready for the business, such as and summary tables. dbt projects use the names staging, intermediate and marts for the same idea. Layers let you rebuild later tables from the raw data.

They help you debug by comparing one layer with the next. And each audience gets the right level of polish. Keep bronze append-only, meaning you only add to it, and keep it as close to the source as possible.

Common trapadding business logic in the bronze layer, or letting dashboards read silver tables that change shape whenever an engineer refactors.

A question to check yourself, an AI practice session and 1 cheat sheet entry come with the full roadmap. Unlock

Resources for this stage

Start with

CourseFree
SQL Tutorial for Data Analysis (formerly Mode)
ThoughtSpot · Beginner
Its advanced section covers window functions, performance tuning and pivoting on realistic data

Practise

LeetCode SQL 50
Fifty graded problems; the window function and aggregation ones match what pipeline SQL needs
Select Star SQL
An interactive book on one real dataset that ends with window functions and self joins

Keep handy

Kimball Dimensional Modeling Techniques
The original definitions of grain, conformed dimensions and SCD types, straight from the source
roadmap.sh: SQL
Check which SQL topics you still lack before moving on

Also worth your time

Data Warehouse Design: Schemas, Steps, and Best Practices (opens in a new tab)Read
Star and snowflake schemas, facts and dimensions, and the steps of a warehouse design in one read