Build RAG Chatbot with LangChain, Faiss, Fireworks AI DeepSeek V3, and voyage-3-large

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.
Faiss: also known as Facebook AI Similarity Search, is an open-source vector search library that allows developers to quickly search for semantically similar multimedia data within a massive dataset of unstructured data. (If you want 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.
Voyage-3-Large: This model is designed for generative tasks, offering enhanced creativity and contextual understanding. With robust training on diverse datasets, it excels in producing coherent narratives and dialogue, making it ideal for applications in storytelling, content creation, and interactive experiences where imaginative output is essential.

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 voyage-3-large

pip install -qU langchain-voyageai

import getpass
import os

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

from langchain-voyageai import VoyageAIEmbeddings

embeddings = VoyageAIEmbeddings(model="voyage-3-large")

Step 4: Install and Set Up Faiss

pip install -qU langchain-community

from langchain_community.vectorstores import FAISS

vector_store = FAISS(embedding_function=embeddings)

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.

Faiss Optimization Tips

To enhance the performance of the Faiss library in a Retrieval-Augmented Generation (RAG) system, begin by selecting the appropriate index type based on your data volume and query speed requirements; for example, using an IVF (Inverted File) index can significantly speed up queries on large datasets by reducing the search space. Optimize your indexing process by using the nlist parameter to partition data into smaller clusters and set an appropriate number of probes (nprobe) during retrieval to balance between speed and accuracy. Ensure the vectors are properly normalized and consider using 16-bit or 8-bit quantization during indexing to reduce memory footprints for large datasets while maintaining reasonable retrieval accuracy. Additionally, consider leveraging GPU acceleration if available, as Faiss highly benefits from parallel processing, leading to faster nearest neighbor searches. Continuous fine-tuning and benchmarking with varying parameters and configurations can guide you in finding the most efficient setup specific to your data characteristics and retrieval requirements.

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.

voyage-3-large optimization tips

voyage-3-large provides enhanced reasoning capabilities, making it ideal for complex RAG tasks requiring deep contextual understanding. Optimize retrieval by implementing a multi-step ranking system that prioritizes highly relevant documents while filtering out lower-quality information. Use structured prompts with clearly delineated context and user queries to improve comprehension. Adjust temperature (0.1–0.3) and fine-tune top-k and top-p settings to maintain accuracy and prevent excessive variability. Take advantage of parallelized inference and request batching to improve processing efficiency. Leverage caching for high-frequency queries to reduce costs and latency. In multi-model setups, deploy voyage-3-large for intricate reasoning tasks while using smaller models for less complex queries to balance cost and performance effectively.

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?

What have you learned? Throughout this tutorial, we’ve taken a deep dive into building a cutting-edge Retrieval-Augmented Generation (RAG) system by seamlessly integrating powerful components: a robust framework with LangChain, the lightning-fast vector database with Faiss, the conversational genius of the Fireworks AI DeepSeek V3 LLM, and the rich semantic understanding provided by the embedding model. Each piece plays a vital role in creating a sophisticated system capable of handling complex queries and generating insightful, contextually relevant responses.

With the LangChain framework orchestrating the interaction between these components, we witnessed how it enhances the overall efficiency and effectiveness of the system. The vector database opened up avenues for rapid searches, enabling your application to deliver information in an instant. Meanwhile, the LLM infused your system with true conversational intelligence, allowing for engaging user interactions that feel natural and intuitive. The embedding model contributed by turning text into rich, semantic representations, paving the way for deeper understanding and relevance in your outputs.

We also shared tips for optimization and introduced a fantastic free cost calculator to help you manage your experimentation expenses. Now that you've seen how these tools come together, the sky's the limit! Take this knowledge and run with it. Build, optimize, and innovate your own RAG applications. Remember, every project you embark on is a step toward mastering these technologies and shaping the future of intelligent systems. So go ahead—let your creativity flow, and watch as you transform your ideas into reality!

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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