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  • Writer's pictureNagesh Singh Chauhan

Retrieval Augmented Generation (RAG) in Large Language Model(LLMs)

Explore how Retrieval Augmented Generation (RAG) is revolutionizing the precision of responses from large language models (LLMs) such as ChatGPT in this in-depth article.


In the dynamic landscape of natural language processing, the quest for generating accurate and contextually relevant information has been an ongoing challenge. Traditional language models, while proficient in various tasks, often fall short when it comes to providing precise, up-to-date, and contextually rich responses. This limitation is particularly evident in scenarios where the latest information is crucial, or domain-specific context plays a pivotal role.

Enter Retrieval Augmented Generation (RAG), an innovative paradigm that addresses these shortcomings by seamlessly integrating the strengths of natural language generation (NLG) and information retrieval (IR). RAG emerges as a transformative solution to the fundamental question: How can we enhance the precision and relevance of information generated by language models?

The Need for Precision and Relevance

Language models, especially large ones like GPT, exhibit remarkable capabilities in generating human-like text based on extensive training datasets. However, their responses may sometimes lack accuracy, especially in scenarios where the information is rapidly evolving or domain-specific. Users often encounter instances where the generated content, while linguistically sound, may be outdated, incomplete, or even inaccurate.

This need for precision and relevance becomes paramount in applications such as question-answering, content creation, and personalized recommendations. Traditional language models, while powerful, operate in a somewhat isolated fashion, relying solely on their pre-trained knowledge and struggling to keep pace with the ever-changing informational landscape.

What is Retrieval Augmented Generation (RAG)?

Retrieval Augmented Generation (RAG) is an innovative method that combines the powerful text-generation capabilities of large language models like GPT with information retrieval functions. This fusion enhances language models' ability to provide accurate and contextually relevant information in response to user queries. By integrating the latest and most pertinent data, RAG addresses the limitations of general-purpose language models, ensuring more precise and reliable outputs.

In simpler terms, large language models are great at many language tasks, but sometimes their responses may not be accurate or up-to-date. This issue, known as hallucination, occurs when the model generates information that may not be entirely correct. RAG tackles this by incorporating information retrieval, making language models more versatile and reliable, especially in cases where the latest and most relevant data is crucial.

How does retrieval augmented generation (RAG) work?

RAG functions by furnishing language models with essential information in a unique manner. Unlike traditional approaches that directly query large language models (LLMs), RAG employs a two-step process. Firstly, it retrieves highly accurate data from a meticulously maintained knowledge library. Next, it utilizes the retrieved context to formulate a response.

Simply put, RAG is a prompt engineering technique used to enhance the output of a Large Language Model (LLM). This is achieved by retrieving additional information from a knowledge base external to the LLM for the purpose of augmenting the prompt input provided to the LLM. Ultimately, these two steps lead to a generation of output far superior than if the LLM had acted alone.

When a user submits a query, the retriever employs vector embeddings (numerical representations) to locate the pertinent document. This approach significantly minimizes the risk of hallucinations and updates the model without the need for costly retraining.

At its core, RAG operates at the confluence of two critical components: Natural Language Generation (NLG) and Information Retrieval (IR).

Components of RAG. Credits

NLG, foundational to advanced language models like GPT, involves generating human-like text based on extensive training on vast datasets. On the other hand, IR sets RAG apart by enabling it to access external knowledge sources, such as databases, websites, or specialized documents, in real-time during text creation.

The synergy between NLG and IR defines RAG's potency. While RAG generates text, it concurrently queries and retrieves information from external sources. This dynamic collaboration enhances the generated content with current and contextually relevant data. Consequently, the text produced by RAG is not only linguistically sound but also deeply informed and contextually relevant.

HR Chatbot Pipeline with RAG. Credits

In practical terms, RAG excels in applications requiring up-to-date and contextually accurate content. It serves as a bridge between general language models and external knowledge sources, facilitating improved content generation, question-answering, personalized recommendations, and more.

Exploring the Impact of RAG

In the realm of artificial intelligence, the demand goes beyond mere correctness; systems must provide answers that are not only generally accurate but also timely and contextually aligned with the user's immediate requirements.

Let's delve into why RAG is transforming the landscape of the Generative AI paradigm:

  1. Dynamic Data Integration: Traditional large language models (LLMs) remain static once trained, lacking mechanisms for real-time updates. RAG introduces a dynamic approach, continuously incorporating fresh data to ensure responses are always grounded in the most recent information available.

  2. Contextual Relevance: RAG goes beyond generic responses by accessing specific organizational or industry databases. This ensures that generated answers are not only accurate but also tailored to the contextual challenges unique to a particular company or industry.

  3. Efficiency and Cost Savings: Unlike the resource-intensive process of retraining LLMs, RAG operates efficiently by harnessing real-time data without modifying the core LLM. This not only saves time but also significantly reduces operational costs.

  4. Transparency and Trust: Modern AI systems must prioritize transparency, and users increasingly seek to understand the origins of the information they receive. RAG addresses this by fetching and presenting data from specific, verifiable sources. This enables users to trace the AI's decision-making process, fostering deeper trust among the user base.

How Do You Implement Retrieval Augmented Generation?

Understanding RAG and its significant impact, let's explore the streamlined steps for implementing a RAG-based system:

  1. Build a Knowledge Repository: Start by aggregating dynamic data sources, ranging from structured databases to unstructured content like blogs and news feeds. Convert this information into a common document format to establish a unified knowledge repository, providing the foundation for the RAG system.

  2. Build the Vector Database: Transform the knowledge repository into numerical representations using embedding models. These models convert textual data into vectors, stored in a vector database for easy retrieval. Pretrained and open-source models, such as those on the Hugging Face leaderboard, ensure simplicity and verifiable performance.

  3. Dynamic Retrieval Mechanism: When users pose queries, RAG utilizes the embedding model to convert each query into a vector, facilitating a search in the document index. The most similar embeddings are then retrieved as a list of documents for the LLM to utilize.

  4. Integrating with the LLM: Merge the retrieved contextual data with the user's original prompt and present it to the LLM. The LLM incorporates this additional context to craft a response.

  5. System Testing: After implementation, conduct thorough testing to identify areas of improvement and ensure the system meets its objectives. Evaluate the vector database's performance using metrics like Recall and Precision. Employ a dataset representing the ground truth to assess how well the returned data aligns with expectations.

RAG vs Fine-tuning — Which Is the Best Tool to Boost Your LLM Application?

Now that we already know about RAG, Fine-tuning, on the other hand, involves training a pre-existing language model on a specific dataset related to the desired task. This process adjusts the model's parameters to adapt it to the nuances of the targeted application. While fine-tuning has proven effective in various scenarios, its success heavily depends on the availability of task-specific data.

RAG & Fine-Tuning LLMs. Credits

Let us also look at the comparative study when it comes to choose between RAG or Fine-tuning:

1. Adaptability to Specific Tasks:

  • RAG: Ideal for scenarios where tasks require real-time, dynamic data or domain-specific context. It excels in applications demanding up-to-date information and contextually rich responses.

  • Fine-tuning: Effective when task-specific datasets are abundant, making it suitable for well-defined tasks with substantial training data.

2. Data Requirements:

  • RAG: Leverages external knowledge sources, reducing the need for extensive task-specific training data. It enhances flexibility by incorporating diverse data types.

  • Fine-tuning: Relies on task-specific data, and its success is contingent on the availability and quality of this data.

3. Real-time Updates:

  • RAG: Allows continuous integration of fresh data, ensuring the model's responses are based on the latest available information.

  • Fine-tuning: Requires retraining whenever there are updates or changes in the task, making it less agile in adapting to dynamic scenarios.

4. Cost and Efficiency:

  • RAG: Minimizes operational costs by avoiding the need for frequent retraining. Efficient in real-time scenarios.

  • Fine-tuning: Can be resource-intensive and costly, particularly when extensive retraining is necessary.

5. Contextual Relevance:

  • RAG: Excels in providing contextually relevant responses by tapping into external knowledge sources.

  • Fine-tuning: Adapts well to tasks with specific training data but may struggle in offering broader context.

The choice between RAG and fine-tuning hinges on the nature of the task, the availability of data, and the requirement for real-time updates. RAG emerges as a potent tool for applications where context, freshness, and versatility are paramount. Its ability to dynamically integrate external knowledge positions it as a game-changer in scenarios where traditional LLMs or fine-tuning might fall short.

Fine-tuning remains a robust approach for tasks with well-defined objectives and abundant task-specific data. Its success lies in its capacity to adapt pre-existing models to the intricacies of specific applications.

RAG Evaluation

As we know RAG operates on two key components: Generation and Retrieval. The retrieval process sets the context, and the LLM carries out the generation by utilizing the retrieved information.

When assessing a RAG pipeline, it becomes crucial to separately and collectively evaluate both these facets. This comprehensive evaluation involves analyzing individual scores to identify specific areas for improvement and deriving an overall score.

Ragas, as evaluative tools, leverage LLMs to assess RAG pipelines. Remarkably, they furnish actionable metrics with minimal reliance on annotated data, offering valuable insights into the system's performance.

Ragas utilizes the following data categories:

  • Question: Represents the queries upon which your RAG pipeline will undergo evaluation.

  • Answer: Denotes the response generated by the RAG pipeline and presented to the user.

  • Contexts: Encompasses the contextual information provided to the LLM to address the given question.

  • Ground Truths: Signifies the authentic answer to the questions, serving as a benchmark.

Ragas produces the subsequent output:

  • Retrieval: Comprises metrics like context_relevancy and context_recall, gauging the efficacy of the retrieval system.

  • Generation: Includes metrics such as faithfulness, measuring hallucinations, and answer_relevancy, assessing the relevance of answers to the given questions.

The most common technique pioneered by frameworks, like Ragas, are Zero-Shot LLM Evaluations. Zero-Shot LLM Evaluation describes prompting a Large Language Model with a prompt template such as: “Please provide a rating on a scale of 1 to 10 of whether these search results are relevant to the query. The query is {query}, the search results are {search_results}”. The visualization below shows how an LLM can be used to evaluate the performance of RAG systems.

When considering the data, it is imperative that the questions mirror those typically posed by users. The illustration below utilizes a dataset featuring fields such as Index, Question, Ground Truth, Answer, and Reference Context.


pip install ragas
pip install tiktoken

from ragas import evaluate
from datasets import Dataset
import os

os.environ["OPENAI_API_KEY"] = "your-openai-key"

# prepare your huggingface dataset in the format
# Dataset({
#     features: ['question', 'contexts', 'answer', 'ground_truths'],
#     num_rows: 25
# })

dataset: Dataset

results = evaluate(dataset)

RAGA produced output:

# {'context_precision': 0.817,
# 'faithfulness': 0.892, 
# 'answer_relevancy': 0.874}


In summary, the incorporation of Retrieval Augmented Generation (RAG) into Large Language Models (LLMs) represents a paradigm shift in natural language processing. By seamlessly merging information retrieval and generation, RAG addresses the limitations of traditional language models, offering heightened contextual relevance and accuracy in responses.

Evaluation of RAG's dual components—Generation and Retrieval—requires a nuanced approach, with tools like Ragas providing valuable metrics such as context_relevancy, context_recall, faithfulness, and answer_relevancy. This comprehensive assessment illuminates areas for improvement and enhances the overall understanding of system performance.


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