Build RAG Chatbot with LangChain, pgvector, Fireworks AI DeepSeek V3, and NVIDIA nv-embed-v1

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.
Pgvector: an open-source extension for PostgreSQL that enables efficient storage and querying of high-dimensional vector data, essential for machine learning and AI applications. Designed to handle embeddings, it supports fast approximate nearest neighbor (ANN) searches using algorithms like HNSW and IVFFlat. Since it is just a vector search add-on to traditional search 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.)
Fireworks AI DeepSeek V3: This advanced AI model specializes in deep data exploration and analysis, providing powerful insights through its robust analytical capabilities. With strengths in pattern recognition and predictive analytics, it is ideal for sectors like finance and healthcare, where uncovering hidden trends and making data-driven decisions are crucial.
NVIDIA nv-embed-v1: This model specializes in generating high-quality embeddings for various applications, such as image and text processing. Its strength lies in efficiently capturing semantic similarities and contextual information. Ideal for tasks like semantic search, recommendation systems, and natural language understanding, it facilitates advanced AI solutions across diverse industries.

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 Fireworks AI DeepSeek V3

pip install -qU "langchain[fireworks]"

import getpass
import os

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

from langchain.chat_models import init_chat_model

llm = init_chat_model("accounts/fireworks/models/deepseek-v3", model_provider="fireworks")

Step 3: Install and Set Up NVIDIA nv-embed-v1

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/nv-embed-v1")

Step 4: Install and Set Up pgvector

pip install -qU langchain-postgres

from langchain_postgres import PGVector

vector_store = PGVector(
    embeddings=embeddings,
    collection_name="my_docs",
    connection="postgresql+psycopg://...",
)

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.

pgvector optimization tips

To optimize pgvector in a Retrieval-Augmented Generation (RAG) setup, consider indexing your vectors using GiST or IVFFlat to significantly speed up search queries and improve retrieval performance. Make sure to leverage parallelization for query execution, allowing multiple queries to be processed simultaneously, especially for large datasets. Optimize memory usage by tuning the vector storage size and using compressed embeddings where possible. To further enhance query speed, implement pre-filtering techniques to narrow down search space before querying. Regularly rebuild indexes to ensure they are up to date with any new data. Fine-tune vectorization models to reduce dimensionality without sacrificing accuracy, thus improving both storage efficiency and retrieval times. Finally, manage resource allocation carefully, utilizing horizontal scaling for larger datasets and offloading intensive operations to dedicated processing units to maintain responsiveness during high-traffic periods.

Fireworks AI DeepSeek V3 optimization tips

DeepSeek V3 is optimized for advanced reasoning and response quality, making it a powerful choice for RAG applications requiring deep contextual understanding. Improve retrieval by implementing multi-stage ranking, ensuring only the most relevant documents are passed as context. Use structured prompts with clear delineation between retrieved content and user queries. Adjust temperature (0.1–0.2) for accuracy and fine-tune top-k/top-p for response control. Minimize latency with precomputed embeddings and caching for commonly queried data. Take advantage of Fireworks AI’s API optimizations to batch multiple requests, reducing processing overhead. Implement dynamic scaling strategies for high-demand scenarios, ensuring model performance remains consistent under load. If used in a multi-tiered architecture, deploy DeepSeek V3 for high-value queries while leveraging smaller models for basic lookups.

NVIDIA nv-embed-v1 Optimization Tips

To optimize the NVIDIA nv-embed-v1 within a Retrieval-Augmented Generation (RAG) setup, ensure you fine-tune your models with domain-specific data to improve relevance and accuracy. Utilize mixed precision training to speed up training times and reduce memory usage. Implement efficient batching techniques to handle larger datasets, maximizing throughput. Leverage NVIDIA’s TensorRT for inference optimization, enabling faster response times during retrieval. Lastly, monitor GPU utilization and experiment with various hyperparameters, such as learning rates and dropout rates, for optimal performance tailored to your application needs.

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 of building a modern RAG system from the ground up! You now understand how to weave together cutting-edge tools like LangChain’s flexible orchestration framework, pgvector’s lightning-fast vector search capabilities, Fireworks AI’s DeepSeek V3 model for generating human-like responses, and NVIDIA’s nv-embed-v1 to turn text into rich numerical representations. These components aren’t just buzzwords—they’re the building blocks of a production-ready pipeline that retrieves precise information and crafts intelligent answers. You’ve seen how LangChain acts as the glue, connecting your data ingestion, embedding generation, and vector storage in pgvector, all while seamlessly integrating with DeepSeek V3 to generate context-aware responses. The tutorial even showed you how to optimize your system, like tuning chunk sizes for better retrieval or balancing speed and accuracy in vector searches—pro tips that’ll save you headaches down the line. And let’s not forget the cherry on top: that free RAG cost calculator to help you estimate expenses and scale smarter!

Now that you’ve got this toolkit, the real magic begins. You’re not just following steps—you’re equipped to create AI applications that feel almost magical. Imagine chatbots that answer like experts, search tools that feel psychic, or personalized content engines that adapt on the fly. The sky’s the limit when you combine these technologies with your creativity. So what’s next? Start experimenting! Tweak parameters, swap models, or layer in new data sources. Use what you’ve learned to build something uniquely yours, whether it’s automating workflows, enhancing customer experiences, or solving problems nobody’s tackled yet. The future of intelligent apps is in your hands—go break things, learn fast, and make something amazing. Your RAG journey is just beginning! 🚀

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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