Build RAG Chatbot with Haystack, Haystack In-memory store, Google Vertex AI Gemini 2.0 Flash, and AmazonBedrock titan-embed-text-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:
- Haystack: An open-source Python framework designed for building production-ready NLP applications, particularly question answering and semantic search systems. Haystack excels at retrieving information from large document collections through its modular architecture that combines retrieval and reader components. Ideal for developers creating search applications, chatbots, and knowledge management systems that require efficient document processing and accurate information extraction from unstructured text.
- Haystack in-memory store: a very simple, in-memory document store with no extra services or dependencies. It is great for experimenting with Haystack, and we do not recommend using it for production. If you want a much more scalable solution for your apps or even enterprise projects, we recommend using Zilliz Cloud, which is a fully managed vector database service built on the open-source Milvusand offers a free tier supporting up to 1 million vectors.)
- Google Vertex AI Gemini 2.0 Flash: A lightweight, high-speed AI model optimized for rapid inference and cost-effective scalability. It excels in real-time applications requiring low latency, such as chatbots, summarization, and data processing, balancing performance with efficiency for high-volume enterprise workloads on Google Cloud.
- AmazonBedrock Titan-Embed-Text-v1: A high-performance embedding model designed to convert text into dense vector representations, enabling semantic search, clustering, and retrieval tasks. Strengths include scalability, multilingual support, and robust accuracy. Ideal for enterprise applications like recommendation systems, document similarity analysis, and AI-driven search engines within AWS environments.
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 Haystack
import os
import requests
from haystack import Pipeline
from haystack.components.converters import MarkdownToDocument
from haystack.components.preprocessors import DocumentSplitter
from haystack.components.writers import DocumentWriter
Step 2: Install and Set Up Google Vertex AI Gemini 2.0 Flash
Using theVertexAIGeminiGenerator
with Haystack requires authentication using Google Cloud Application Default Credentials (ADCs). This means your application must be set up with credentials that allow it to access Google Cloud services. If you're not sure how to configure ADCs, check the official Google documentation for setup instructions.
It's important to use a Google Cloud account that has the right permissions to access a project with Google Vertex AI endpoints. Without proper access, the generator won’t work as expected.
To find your project ID, you can either look it up in the Google Cloud Console under the resource manager or run the following command in your terminal.
Now let's install and set up this model.
pip install google-vertex-haystack
from haystack_integrations.components.generators.google_vertex import VertexAIGeminiGenerator
generator = VertexAIGeminiGenerator(model="gemini-2.0-flash-001")
Step 3: Install and Set Up AmazonBedrock titan-embed-text-v1
Amazon Bedrock is a fully managed service that makes high-performing foundation models from leading AI startups and Amazon available through a unified API.
To use embedding models on Amazon Bedrock for text and document embedding together with Haystack, you need to initialize an AmazonBedrockTextEmbedder
and AmazonBedrockDocumentEmbedder
with the model name, the AWS credentials (aws_access_key_id
, aws_secret_access_key
, and aws_region_name
) should be set as environment variables, be configured as described above or passed as Secret arguments. Note, make sure the region you set supports Amazon Bedrock.
Now, let's start installing and setting up models with Amazon Bedrock.
pip install amazon-bedrock-haystack
import os
from haystack_integrations.components.embedders.amazon_bedrock import AmazonBedrockTextEmbedder
from haystack_integrations.components.embedders.amazon_bedrock import AmazonBedrockDocumentEmbedder
from haystack.dataclasses import Document
os.environ["AWS_ACCESS_KEY_ID"] = "..."
os.environ["AWS_SECRET_ACCESS_KEY"] = "..."
os.environ["AWS_DEFAULT_REGION"] = "us-east-1" # just an example
text_embedder = AmazonBedrockTextEmbedder(model="amazon.titan-embed-text-v1",
input_type="search_query"
document_embedder = AmazonBedrockDocumentEmbedder(model="amazon.titan-embed-text-v1",
input_type="search_document"
Step 4: Install and Set Up Haystack In-memory store
from haystack.document_stores.in_memory import InMemoryDocumentStore
from haystack.components.retrievers import InMemoryEmbeddingRetriever
document_store = InMemoryDocumentStore()
retriever=InMemoryEmbeddingRetriever(document_store=document_store))
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 your own dataset to customize your RAG chatbot.
url = 'https://raw.githubusercontent.com/milvus-io/milvus-docs/refs/heads/v2.5.x/site/en/about/overview.md'
example_file = 'example_file.md'
response = requests.get(url)
with open(example_file, 'wb') as f:
f.write(response.content)
file_paths = [example_file] # You can replace it with your own file paths.
indexing_pipeline = Pipeline()
indexing_pipeline.add_component("converter", MarkdownToDocument())
indexing_pipeline.add_component("splitter", DocumentSplitter(split_by="sentence", split_length=2))
indexing_pipeline.add_component("embedder", document_embedder)
indexing_pipeline.add_component("writer", DocumentWriter(document_store))
indexing_pipeline.connect("converter", "splitter")
indexing_pipeline.connect("splitter", "embedder")
indexing_pipeline.connect("embedder", "writer")
indexing_pipeline.run({"converter": {"sources": file_paths}})
# print("Number of documents:", document_store.count_documents())
question = "What is Milvus?" # You can replace it with your own question.
retrieval_pipeline = Pipeline()
retrieval_pipeline.add_component("embedder", text_embedder)
retrieval_pipeline.add_component("retriever", retriever)
retrieval_pipeline.connect("embedder", "retriever")
retrieval_results = retrieval_pipeline.run({"embedder": {"text": question}})
# for doc in retrieval_results["retriever"]["documents"]:
# print(doc.content)
# print("-" * 10)
from haystack.utils import Secret
from haystack.components.builders import PromptBuilder
retriever=InMemoryEmbeddingRetriever(document_store=document_store)
text_embedder = AmazonBedrockTextEmbedder(model="amazon.titan-embed-text-v1",
input_type="search_query"
prompt_template = """Answer the following query based on the provided context. If the context does
not include an answer, reply with 'I don't know'.\n
Query: {{query}}
Documents:
{% for doc in documents %}
{{ doc.content }}
{% endfor %}
Answer:
"""
rag_pipeline = Pipeline()
rag_pipeline.add_component("text_embedder", text_embedder)
rag_pipeline.add_component("retriever", retriever)
rag_pipeline.add_component("prompt_builder", PromptBuilder(template=prompt_template))
rag_pipeline.add_component("generator", generator)
rag_pipeline.connect("text_embedder.embedding", "retriever.query_embedding")
rag_pipeline.connect("retriever.documents", "prompt_builder.documents")
rag_pipeline.connect("prompt_builder", "generator")
results = rag_pipeline.run({"text_embedder": {"text": question}, "prompt_builder": {"query": question},})
print('RAG answer:\n', results["generator"]["replies"][0])
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.
Haystack optimization tips
To optimize Haystack in a RAG setup, ensure you use an efficient retriever like FAISS or Milvus for scalable and fast similarity searches. Fine-tune your document store settings, such as indexing strategies and storage backends, to balance speed and accuracy. Use batch processing for embedding generation to reduce latency and optimize API calls. Leverage Haystack's pipeline caching to avoid redundant computations, especially for frequently queried documents. Tune your reader model by selecting a lightweight yet accurate transformer-based model like DistilBERT to speed up response times. Implement query rewriting or filtering techniques to enhance retrieval quality, ensuring the most relevant documents are retrieved for generation. Finally, monitor system performance with Haystack’s built-in evaluation tools to iteratively refine your setup based on real-world query performance.
Haystack in-memory store optimization tips
Haystack in-memory store is just a very simple, in-memory document store with no extra services or dependencies. We recommend that you just experiment it with RAG pipeline within your Haystack framework, and we do not recommend using it for production. If you want a much more scalable solution for your apps or even enterprise projects, we recommend using Zilliz Cloud, which is a fully managed vector database service built on the open-source Milvusand offers a free tier supporting up to 1 million vectors
Google Vertex AI Gemini 2.0 Flash optimization tips
To optimize Gemini 2.0 Flash in RAG, balance chunk size for retrieved documents—smaller chunks (200-400 tokens) improve precision, while larger ones preserve context. Use preprocessing to clean text, remove noise, and add metadata (e.g., timestamps) for relevance scoring. Adjust model parameters: lower temperature
(0.2-0.5) for factual outputs, and limit max_output_tokens
to reduce latency. Batch process embeddings to cut API calls. Cache frequent queries and responses. Fine-tune with domain-specific data if available. Monitor latency and cost via Vertex AI’s tools, and use asynchronous calls for non-blocking operations.
AmazonBedrock titan-embed-text-v1 optimization tips
To optimize titan-embed-text-v1 in a RAG setup, preprocess inputs by removing redundant whitespace and truncating excessively long texts to fit its 8K-token limit. Use batch embedding requests to reduce latency and costs. Fine-tune chunking strategies to balance context retention (e.g., 512-token segments) and avoid fragmentation. Normalize embeddings to improve retrieval accuracy. Leverage metadata filtering to refine retrieved results. Test newer model versions for performance gains. Cache frequent or repeated queries to minimize redundant computations. Monitor embedding quality via cosine similarity thresholds and adjust retrieval thresholds dynamically.
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
What Have You Learned?
By now, you’ve unlocked the magic of building a RAG system from the ground up—and that’s no small feat! You learned how Haystack acts as the backbone, seamlessly orchestrating every step of the pipeline. The tutorial showed you how Haystack’s flexibility lets you plug in components like the lightning-fast Haystack In-Memory Store for vector storage, making retrieval efficient and straightforward. Then, you saw how the Amazon Titan Embed Text v1 model transforms raw text into rich, meaningful embeddings, giving your system the ability to "understand" context. Pair that with Google Vertex AI’s Gemini 2.0 Flash—a powerhouse LLM that generates crisp, human-like answers—and you’ve got a RAG pipeline that feels almost alive. The best part? You discovered how these pieces fit together like puzzle pieces, from ingesting data to querying results, all while keeping things lightweight and scalable.
But wait, there’s more! You also picked up pro tips for optimizing performance, like tweaking chunk sizes or experimenting with hybrid retrieval strategies to balance speed and accuracy. And let’s not forget the free RAG cost calculator—your secret weapon for estimating expenses upfront, so you can build smarter without surprises. Imagine what’s next: customizing this setup for niche domains, enhancing user experiences, or even scaling to handle millions of queries. The tools are in your hands, and the possibilities are endless. So, what are you waiting for? Dive back in, tweak those parameters, and start creating RAG applications that wow users and push boundaries. The future of intelligent systems is yours to shape—go build something amazing! 🚀
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
We'd Love to Hear What You Think!
We’d love to hear your thoughts! 🌟 Leave your questions or comments below or join our vibrant Milvus Discord community to share your experiences, ask questions, or connect with thousands of AI enthusiasts. Your journey matters to us!
If you like this tutorial, show your support by giving our Milvus GitHub repo a star ⭐—it means the world to us and inspires us to keep creating! 💖
- Introduction to RAG
- Key Components We'll Use for This RAG Chatbot
- Step 1: Install and Set Up Haystack
- Step 2: Install and Set Up Google Vertex AI Gemini 2.0 Flash
- Step 3: Install and Set Up AmazonBedrock titan-embed-text-v1
- Step 4: Install and Set Up Haystack In-memory store
- Step 5: Build a RAG Chatbot
- Optimization Tips
- RAG Cost Calculator: A Free Tool to Calculate Your Cost in Seconds
- What Have You Learned?
- Further Resources
- We'd Love to Hear What You Think!
Content
Vector Database at Scale
Zilliz Cloud is a fully-managed vector database built for scale, perfect for your RAG apps.
Try Zilliz Cloud for Free