Build RAG Chatbot with LangChain, OpenSearch, Together AI Mixtral 8x7B Instruct v0.1, and NVIDIA llama-3.2-nv-embedqa-1b-v2

Introduction to RAG

Retrieval-Augmented Generation (RAG) is a game-changer for GenAI applications, especially in conversational AI. It combines the power of pre-trained large language models (LLMs) like OpenAI’s GPT with external knowledge sources stored in vector databases such as Milvus and Zilliz Cloud, allowing for more accurate, contextually relevant, and up-to-date response generation. A RAG pipeline usually consists of four basic components: a vector database, an embedding model, an LLM, and a framework.

Key Components We'll Use for This RAG Chatbot

This tutorial shows you how to build a simple RAG chatbot in Python using the following components:

LangChain: An open-source framework that helps you orchestrate the interaction between LLMs, vector stores, embedding models, etc, making it easier to integrate a RAG pipeline.
OpenSearch: An open-source search and analytics suite derived from Elasticsearch. It offers robust full-text search and real-time analytics, with vector search available as an add-on for similarity-based queries, extending its capabilities to handle high-dimensional data. Since it is just a vector search add-on rather than a purpose-built vector database, it lacks scalability and availability and many other advanced features required by enterprise-level applications. Therefore, if you prefer a much more scalable solution or hate to manage your own infrastructure, we recommend using Zilliz Cloud, which is a fully managed vector database service built on the open-source Milvus and offers a free tier supporting up to 1 million vectors.)
Together AI Mixtral 8x7B Instruct v0.1: This model offers a powerful blend of instruction-based learning and advanced natural language understanding. With its 8x7B architecture, it excels in generating coherent and context-aware responses. Ideal for applications like chatbots, content creation, and educational tools where user guidance and high-quality interaction are essential.
NVIDIA llama-3.2-nv-embedqa-1b-v2: This AI model is designed for advanced question-answering tasks, leveraging NVIDIA's LLaMA architecture. It excels in embedding-based question retrieval and provides high accuracy in understanding context. Ideal for knowledge-intensive applications, it enhances customer support, educational tools, and research assistance.

By the end of this tutorial, you’ll have a functional chatbot capable of answering questions based on a custom knowledge base.

Note: Since we may use proprietary models in our tutorials, make sure you have the required API key beforehand.

Step 1: Install and Set Up LangChain

%pip install --quiet --upgrade langchain-text-splitters langchain-community langgraph

Step 2: Install and Set Up Together AI Mixtral 8x7B Instruct v0.1

pip install -qU "langchain[together]"

import getpass
import os

if not os.environ.get("TOGETHER_API_KEY"):
  os.environ["TOGETHER_API_KEY"] = getpass.getpass("Enter API key for Together AI: ")

from langchain.chat_models import init_chat_model

llm = init_chat_model("mistralai/Mixtral-8x7B-Instruct-v0.1", model_provider="together")

Step 3: Install and Set Up NVIDIA llama-3.2-nv-embedqa-1b-v2

pip install -qU langchain-nvidia-ai-endpoints

import getpass
import os

if not os.environ.get("NVIDIA_API_KEY"):
  os.environ["NVIDIA_API_KEY"] = getpass.getpass("Enter API key for NVIDIA: ")

from langchain_nvidia_ai_endpoints import NVIDIAEmbeddings

embeddings = NVIDIAEmbeddings(model="nvidia/llama-3.2-nv-embedqa-1b-v2")

Step 4: Install and Set Up OpenSearch

pip install --upgrade --quiet  opensearch-py langchain-community

from langchain_community.vectorstores import OpenSearchVectorSearch
opensearch_vector_search = OpenSearchVectorSearch(
    "http://localhost:9200",
    "embeddings",
    embedding_function
)

Step 5: Build a RAG Chatbot

Now that you’ve set up all components, let’s start to build a simple chatbot. We’ll use the Milvus introduction doc as a private knowledge base. You can replace it with your own dataset to customize your RAG chatbot.

import bs4
from langchain import hub
from langchain_community.document_loaders import WebBaseLoader
from langchain_core.documents import Document
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langgraph.graph import START, StateGraph
from typing_extensions import List, TypedDict

# Load and chunk contents of the blog
loader = WebBaseLoader(
    web_paths=("https://milvus.io/docs/overview.md",),
    bs_kwargs=dict(
        parse_only=bs4.SoupStrainer(
            class_=("doc-style doc-post-content")
        )
    ),
)

docs = loader.load()

text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=200)
all_splits = text_splitter.split_documents(docs)

# Index chunks
_ = vector_store.add_documents(documents=all_splits)

# Define prompt for question-answering
prompt = hub.pull("rlm/rag-prompt")


# Define state for application
class State(TypedDict):
    question: str
    context: List[Document]
    answer: str


# Define application steps
def retrieve(state: State):
    retrieved_docs = vector_store.similarity_search(state["question"])
    return {"context": retrieved_docs}


def generate(state: State):
    docs_content = "\n\n".join(doc.page_content for doc in state["context"])
    messages = prompt.invoke({"question": state["question"], "context": docs_content})
    response = llm.invoke(messages)
    return {"answer": response.content}


# Compile application and test
graph_builder = StateGraph(State).add_sequence([retrieve, generate])
graph_builder.add_edge(START, "retrieve")
graph = graph_builder.compile()

Test the Chatbot

Yeah! You've built your own chatbot. Let's ask the chatbot a question.

response = graph.invoke({"question": "What data types does Milvus support?"})
print(response["answer"])

Example Output

Milvus supports various data types including sparse vectors, binary vectors, JSON, and arrays. Additionally, it handles common numerical and character types, making it versatile for different data modeling needs. This allows users to manage unstructured or multi-modal data efficiently.

Optimization Tips

As you build your RAG system, optimization is key to ensuring peak performance and efficiency. While setting up the components is an essential first step, fine-tuning each one will help you create a solution that works even better and scales seamlessly. In this section, we’ll share some practical tips for optimizing all these components, giving you the edge to build smarter, faster, and more responsive RAG applications.

LangChain optimization tips

To optimize LangChain, focus on minimizing redundant operations in your workflow by structuring your chains and agents efficiently. Use caching to avoid repeated computations, speeding up your system, and experiment with modular design to ensure that components like models or databases can be easily swapped out. This will provide both flexibility and efficiency, allowing you to quickly scale your system without unnecessary delays or complications.

OpenSearch optimization tips

To optimize OpenSearch in a Retrieval-Augmented Generation (RAG) setup, fine-tune indexing by enabling efficient mappings and reducing unnecessary stored fields. Use HNSW for vector search to speed up similarity queries while balancing recall and latency with appropriate ef_search and ef_construction values. Leverage shard and replica settings to distribute load effectively, and enable caching for frequent queries. Optimize text-based retrieval with BM25 tuning and custom analyzers for better relevance. Regularly monitor cluster health, index size, and query performance using OpenSearch Dashboards and adjust configurations accordingly.

Together AI Mixtral 8x7B Instruct v0.1 optimization tips

Together AI’s Mixtral 8x7B Instruct v0.1 uses a mixture-of-experts (MoE) architecture to balance efficiency and performance. Optimize retrieval by dynamically adjusting the number of retrieved documents based on query complexity to prevent overloading the context window. Structure prompts effectively, ensuring that critical details are at the start of the input to guide the model’s focus. Use a temperature of 0.1–0.3 for factual accuracy while tweaking top-k and top-p for balanced response generation. Together AI’s inference stack allows for optimized execution, so enable expert pruning to limit active pathways when full capacity isn’t needed. Implement caching strategies for common queries to minimize redundant processing. If integrating multiple models, use Mixtral 8x7B for medium-to-high complexity reasoning while offloading simpler queries to smaller, more efficient models.

NVIDIA llama-3.2-nv-embedqa-1b-v2 optimization tips

To optimize the performance of the NVIDIA llama-3.2-nv-embedqa-1b-v2 in a Retrieval-Augmented Generation setup, consider employing mixed precision training to enhance computational efficiency while maintaining model accuracy. Utilize efficient indexing and retrieval methods, such as FAISS, to quickly access relevant documents, minimizing response time. Tune the hyperparameters, especially the learning rate and batch size, based on validation metrics to improve convergence speed. Implement caching strategies to store frequently accessed data and results for faster retrieval. Regularly profile the model to identify bottlenecks and make necessary adjustments. Finally, leverage NVIDIA’s TensorRT for optimized inference, ensuring that your setup benefits from accelerated performance on compatible hardware.

By implementing these tips across your components, you'll be able to enhance the performance and functionality of your RAG system, ensuring it’s optimized for both speed and accuracy. Keep testing, iterating, and refining your setup to stay ahead in the ever-evolving world of AI development.

RAG Cost Calculator: A Free Tool to Calculate Your Cost in Seconds

Estimating the cost of a Retrieval-Augmented Generation (RAG) pipeline involves analyzing expenses across vector storage, compute resources, and API usage. Key cost drivers include vector database queries, embedding generation, and LLM inference.

RAG Cost Calculator is a free tool that quickly estimates the cost of building a RAG pipeline, including chunking, embedding, vector storage/search, and LLM generation. It also helps you identify cost-saving opportunities and achieve up to 10x cost reduction on vector databases with the serverless option.

Calculate your RAG cost now.

Calculate your RAG cost

What Have You Learned?

By diving into this tutorial, you’ve unlocked the power to build a RAG system from the ground up using cutting-edge tools! You learned how LangChain acts as the glue, elegantly orchestrating the flow of data between components. With OpenSearch as your vector database, you saw how to store and retrieve dense embeddings efficiently, ensuring lightning-fast similarity searches that ground your LLM’s responses in real-world data. The NVIDIA llama-3.2-nv-embedqa-1b-v2 embedding model transformed text into rich numerical representations, capturing semantic meaning so your system understands context deeply. Then, Together AI’s Mixtral 8x7B Instruct v0.1 stepped in as the brain, synthesizing retrieved information into coherent, human-like answers—proving how a powerful LLM can turn raw data into actionable insights. Along the way, you discovered optimization tricks like chunking strategies and metadata filtering to boost performance and cost-efficiency, plus how the free RAG cost calculator helps you balance speed, accuracy, and budget like a pro.

Now you’re equipped to create RAG pipelines that feel almost magical! Whether you’re building chatbots, research tools, or personalized recommendation engines, you’ve got the toolkit to make it happen. Remember, the real magic lies in experimentation—tweak parameters, test different models, and iterate to find what works best for your use case. The future of AI-driven applications is in your hands, and with RAG, you’re not just answering questions—you’re building systems that learn, adapt, and grow. So fire up your IDE, play with these tools, and let your creativity run wild. The next breakthrough in intelligent applications could be yours. Happy building—your journey into the RAG revolution has just begun! 🚀

Further Resources

🌟 In addition to this RAG tutorial, unleash your full potential with these incredible resources to level up your RAG skills.

How to Build a Multimodal RAG | Documentation
How to Enhance the Performance of Your RAG Pipeline
Graph RAG with Milvus | Documentation
How to Evaluate RAG Applications - Zilliz Learn
Generative AI Resource Hub | Zilliz

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