Building a Local RAG Prototype with Qwen15, LangChain, Ollama, and ChromaDB

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RAG (Retrieval-Augmented Generation) is one of the most promising ways to integrate AI into real-world workflows. Many teams struggle with where to start, so I built a local prototype using Qwen1.5, LangChain, Ollama, and ChromaDB—completely cloud-free, API-free, and frictionless.

Here’s a step-by-step breakdown of the pipeline, along with the GitHub repository:
➡️ Full Process & GitHub Repo

You Should Know:

1. Setting Up the Environment

Before running the RAG pipeline, ensure you have the following installed:

 Install Python dependencies 
pip install langchain ollama chromadb qwen1.5

Pull the Qwen1.5 model via Ollama 
ollama pull qwen1.5 

2. Initializing ChromaDB for Vector Storage

ChromaDB is used for storing and retrieving document embeddings.

from langchain.vectorstores import Chroma 
from langchain.embeddings import OllamaEmbeddings

Initialize embeddings 
embeddings = OllamaEmbeddings(model="qwen1.5")

Create a ChromaDB instance 
vector_db = Chroma.from_texts( 
texts=["Your document text here..."], 
embedding=embeddings, 
persist_directory="./chroma_db" 
) 

3. Configuring LangChain for RAG

LangChain orchestrates the retrieval and generation process.

from langchain.chains import RetrievalQA 
from langchain.llms import Ollama

Load the Qwen1.5 model 
llm = Ollama(model="qwen1.5")

Create a retriever from ChromaDB 
retriever = vector_db.as_retriever()

Build the RAG pipeline 
qa_chain = RetrievalQA.from_chain_type( 
llm=llm, 
chain_type="stuff", 
retriever=retriever 
)

Query the RAG model 
response = qa_chain.run("What is RAG?") 
print(response) 

4. Running the Pipeline Locally

Execute the script and test with custom queries:

python rag_pipeline.py 

5. Optimizing Performance

  • Use GPU acceleration for faster embeddings (export CUDA_VISIBLE_DEVICES=0).
  • Fine-tune retrieval parameters (k=3 for top 3 documents).

What Undercode Say:

This local RAG prototype demonstrates how to leverage Qwen1.5, LangChain, Ollama, and ChromaDB without relying on cloud APIs. Key takeaways:
– Privacy-first AI: No data leaves your machine.
– Cost-effective: Avoids API fees.
– Customizable: Adaptable to domain-specific documents.

For further improvements, consider:

  • Adding hybrid search (keyword + semantic).
  • Implementing query expansion for better retrieval.

Prediction:

As RAG adoption grows, more enterprises will shift toward self-hosted AI solutions to maintain data control and reduce costs. Expect tighter integrations between local LLMs and enterprise knowledge bases in 2024-2025.

Expected Output:

RAG (Retrieval-Augmented Generation) is a method that enhances AI responses by retrieving relevant documents before generating an answer, improving accuracy and context awareness. 

➡️ GitHub Repo: https://lnkd.in/enyys-ze

IT/Security Reporter URL:

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Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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