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7 min read

Build a Mini RAG System: Hands-On Workshop

By Dorian Laurenceau

Updated

📅 Last reviewed: April 24, 2026. Updated with April 2026 findings and community feedback.

Theory without practice is just trivia. In this workshop, you will build a complete RAG system, a knowledge base that answers questions about your own documents. By the end, you will understand every component of the RAG pipeline and how to tune it.

Workshop Overview

What We Are Building

A document Q and A system in 5 steps

Step 1, Load Documents

Load a set of documents (markdown files, PDFs, or plain text) and prepare them for processing.
code
// Pseudocode for the workshop
const docs = loadDocuments('./knowledge-base/')
console.log('Loaded', docs.length, 'documents')

💡 Start small: 5-10 documents. You can scale later.

1/5

Tuning Your RAG System

Embedding Models for RAG

ModelDimensionsSpeedQualityCost
text-embedding-3-small (OpenAI)1,536FastGood$0.02/1M tokens
text-embedding-3-large (OpenAI)3,072MediumExcellent$0.13/1M tokens
all-MiniLM-L6-v2 (Open Source)384Very FastGoodFree (self-hosted)
Cohere embed-v31,024FastExcellent$0.10/1M tokens

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Quick Check

Why does accuracy decrease when K (number of retrieved chunks) is too high?

Evaluation: How Good Is Your RAG?

Click to expand

Common Issues and Fixes

RAG Troubleshooting Guide

ProblemSymptomFix
Wrong chunks retrievedAnswer is about wrong topicImprove chunking strategy, add metadata filters
Answer includes hallucinationClaims not in source docsStrengthen "answer ONLY from context" instruction
Incomplete answersMissing key informationIncrease K, improve chunk overlap, check chunking boundaries
Slow retrievalQuery takes secondsAdd vector index (HNSW), reduce embedding dimensions
Stale answersDocument was updated but RAG gives old infoSet up automated re-embedding on document change

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Scaling Beyond the Workshop

Click to expand

Test Your Understanding

Question 1 of 5.

Mini RAG Workshop Check

0 / 5 answered

Q1.What are the 5 steps to build a RAG system?

5 questions remaining

Continue Learning

You have built your first RAG system. In the next module, you will learn about AI Agents, systems that can reason, use tools, and take actions autonomously using the ReAct framework.


Continue to ReAct Method: AI Agents Explained to understand autonomous AI systems.

Go deeper — free guide

Module 5 — RAG (Retrieval-Augmented Generation)

Ground AI responses in your own documents and data sources.

D

Dorian Laurenceau

Full-Stack Developer & Learning Designer

Full-stack web developer and learning designer. I spent 4 years as a freelance full-stack developer and 4 years teaching React, JavaScript, HTML/CSS and WordPress to adult learners. Today I design learning paths in web development and AI, grounded in learning science. I founded learn-prompting.fr to make AI practical and accessible, and built the Bluff app to gamify political transparency.

Prompt EngineeringLLMsFull-Stack DevelopmentLearning DesignReact
Published: March 9, 2026Updated: April 24, 2026

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FAQ

What will I learn in this RAG guide?+

Build a complete Retrieval-Augmented Generation system from scratch. Load documents, create embeddings, implement vector search, and generate grounded answers step by step.