Unlocking the Power of RAG with Ollama, LangChain & ChromaDB: A Step-by-Step Tutorial

Introduction

In the rapidly evolving landscape of AI, combining retrieval mechanisms with generative models—commonly known as Retrieval-Augmented Generation (RAG)—is becoming a foundational approach to create grounded, factual, and context-aware responses.

Git Repo – https://github.com/bikashkaushik/ollama-rag-tutorial

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Why This Tutorial Matters

• Achieve factual accuracy by grounding large language model responses in real-world documents—a key challenge in generative AI.

• Use open-source, locally run components to ensure full control over data privacy, cost-efficiency, and latency.

• Lean on familiar Python libraries like LangChain and ChromaDB to streamline development and deployment.

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Overview of the Tutorial

Here’s what the repository includes and how it all connects:

1. Environment Setup
   Set up a clean Python environment and install required packages, including:
pip install langchain
   pip install langchain-community
   pip install langchain-ollama
   pip install langchain-chroma
   pip install chromadb
   pip install pypdf

   This ensures you have everything from embedding and RAG orchestration (LangChain) to a vector store (ChromaDB) and document parsing (pypdf). GitHub

2. Installing & Configuring Ollama
   

   1. Download and install Ollama to run models locally.

   2. Pull and start the embedding model:
      ollama pull nomic-embed-text


   3. Pull and run the language generation model:
      ollama run mistral


   This lets you run core inference and embedding services without relying on external API endpoints. GitHub

3. Embedding Function
   The tutorial includes a get_embedding_function.py script to wrap the Ollama embedding model. This function is essential for converting raw text into vector embeddings that drive similarity search.

4. Building the Vector Store
   Through populate_database.py, you’ll parse source documents, generate embeddings, and store them in ChromaDB. This setup forms the searchable knowledge base for RAG to tap into.

   Example Usage
   python populate_database.py –reset # Clears and rebuilds the database from scratch.
   python populate_database.py # Adds new or updated documents without wiping existing data.

5. Querying with Retrieval-Augmented Generation
   query_data.py orchestrates the full RAG workflow: retrieve relevant content from ChromaDB, feed it—along with your query—into the Mistral LLM via LangChain, and receive grounded, context-aware responses.

   Example Command Usage
   python query_data.py “What is the RAG technique in AI?”

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Why You Should Try It

• Privacy-first: Run everything locally—no external API dependencies.

• Modular: Choose which components to swap, upgrade, or extend (e.g., swap the vector store, embedding model, or LLM).

• Practical foundation: Use this as a springboard to build internal helpdesks, document QA bots, research assistants, and more.

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Call to the Community

If you’re working on similar RAG implementations—or curious to explore the Ollama, LangChain, or ChromaDB ecosystems—let’s connect! I’d love to compare notes, share learnings, or even co-create something exciting.

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Conclusion

This is more than just a walkthrough—it’s an invitation to experiment with cutting-edge, local-first AI techniques. By merging retrieval, embeddings, and generation in an open-source stack, you can bring smarter, grounded interactions to your applications—while staying in control of your stack.