Truy xuất đệ quy cho RAG: Triển khai với LlamaIndex

Truy xuất đệ quy là gì?

Thay vì chỉ embedding các đoạn thô của tài liệu và truy xuất dựa trên độ tương đồng, truy xuất đệ quy hoạt động bằng cách embedding trước các bản tóm tắt của tài liệu và liên kết chúng với các đoạn đầy đủ. Khi có truy vấn, hệ thống trước tiên truy xuất các bản tóm tắt liên quan rồi đào sâu để tìm các đoạn thông tin có liên quan.

Phương pháp này cung cấp thêm ngữ cảnh cho hệ thống trước khi đưa ra các đoạn cuối cùng, nhờ đó tìm thông tin phù hợp tốt hơn.

Triển khai truy xuất đệ quy bằng LlamaIndex

Trong phần này, chúng tôi sẽ hướng dẫn bạn quy trình từng bước để triển khai truy xuất đệ quy bằng LlamaIndex, bắt đầu từ việc nạp tài liệu cho đến chạy truy vấn với truy xuất đệ quy.

Bước 1: Nạp và chuẩn bị tài liệu

Đầu tiên, chúng ta nạp tài liệu vào hệ thống bằng SimpleDirectoryReader. Mỗi tài liệu được gán tiêu đề và metadata (như danh mục) để việc lọc sau này dễ dàng hơn. Các tài liệu đã nạp được lưu vào một dictionary để truy cập thuận tiện.

from llama_index.core import SimpleDirectoryReader

# Document titles and metadata
article_titles = ["How to Do Great Work", "Having Kids", "How to Lose Time and Money"]
article_metadatas = {
    "How to Do Great Work": {
        "category": "self-help",
    },
    "Having Kids": {
        "category": "self-help",
    },
    "How to Lose Time and Money": {
        "category": "self-help",
    },
}

# Load documents and update with metadata
docs_dict = {}
for title in article_titles:
    doc = SimpleDirectoryReader(
        input_files=[f"llamaindex-data/{title}.txt"]
    ).load_data()[0]
    doc.metadata.update(article_metadatas[title])
    docs_dict[title] = doc

docs_dictĐược hỗ trợ bởi

Để dễ đọc, tôi sẽ rút gọn đầu ra bên dưới:

{'How to Do Great Work': Document(id_='e26a2fcc-77d2-43e8-968b-f893944907dc', embedding=None, metadata={'file_path': 'llamaindex-data/How to Do Great Work.txt', 'file_name': 'How to Do Great Work.txt', 'file_type': 'text/plain', 'file_size': 59399, 'creation_date': '2024-09-18', 'last_modified_date': '2024-09-18', 'category': 'self-help'}, excluded_embed_metadata_keys=['file_name', 'file_type', 'file_size', 'creation_date', 'last_modified_date', 'last_accessed_date'], excluded_llm_metadata_keys=['file_name', 'file_type', 'file_size', 'creation_date', 'last_modified_date', 'last_accessed_date'], relationships={}, text='July 2023\\n\\nIf you collected lists of techniques for doing great work in a lot of different fields, what would the intersection look like? I decided to find out by making it.\\n\\nPartly my goal was to create a guide that could be used by someone working in any field. But I was also curious about the shape of the intersection. And one thing this exercise shows is that it does have a definite shape; it\\'s not just a point labelled "work hard."\\n\\nThe following recipe assumes you\\'re very ambitious.\\n\\n\\n\\n\\n\\nThe first step is to decide what to work on. The work you choose needs to have three qualities: it has to be something you have a natural aptitude for, that you have a deep interest in, and that offers scope to do great work.\\n\\nIn practice you don\\'t have to worry much about the third criterion. Ambitious people are if anything already too conservative about it. So all you need to do is find something you have an aptitude for and great interest in. [1]\\n\\nThat sounds straightforward, but it\\'s often quite difficult. When you\\'re young you don\\'t know what you\\'re good at or what different kinds of work are like. Some kinds of work you end up doing may not even exist yet. So while some people know what they want to do at 14, most have to figure it out.\\n\\nThe way to figure out what to work on is by working. If you\\'re not sure what to work on, guess. But pick something and get going. You\\'ll probably guess wrong some of the time, but that\\'s fine. It\\'s good to know about multiple things; some of the biggest discoveries come from noticing connections between different fields.\\n\\n
…
(truncated)Được hỗ trợ bởi

Bước 2: Thiết lập LLM và chia đoạn

Tiếp theo, chúng ta khởi tạo mô hình ngôn ngữ lớn (LLM) bằng GPT-4o Mini của OpenAI và cấu hình bộ tách câu để chia tài liệu thành các đoạn nhỏ hơn phục vụ embedding. Chúng ta cũng thiết lập callback manager để theo dõi quá trình.

from llama_index.llms.openai import OpenAI
from llama_index.core.callbacks import LlamaDebugHandler, CallbackManager
from llama_index.core.node_parser import SentenceSplitter

# Initialize LLM and chunk splitter
llm = OpenAI("gpt-4o-mini")
callback_manager = CallbackManager([LlamaDebugHandler()])
splitter = SentenceSplitter(chunk_size=256)Được hỗ trợ bởi

Bước 3: Xây dựng chỉ mục vector và tạo tóm tắt

Với mỗi tài liệu, chúng ta tạo một chỉ mục vector, cho phép sau này truy xuất các đoạn tài liệu liên quan dựa trên độ tương đồng. Bản tóm tắt của mỗi tài liệu được LLM tạo ra. Các bản tóm tắt này được lưu dưới dạng IndexNode.

from llama_index.core import VectorStoreIndex, SummaryIndex
from llama_index.core.schema import IndexNode

# Define top-level nodes and vector retrievers
nodes = []
vector_query_engines = {}
vector_retrievers = {}

for title in article_titles:
    # build vector index
    vector_index = VectorStoreIndex.from_documents(
        [docs_dict[title]],
        transformations=[splitter],
        callback_manager=callback_manager,
    )
    
    # define query engines
    vector_query_engine = vector_index.as_query_engine(llm=llm)
    vector_query_engines[title] = vector_query_engine
    vector_retrievers[title] = vector_index.as_retriever(similarity_top_k=3)
    # save summaries
    out_path = Path("summaries") / f"{title}.txt"
    if not out_path.exists():
        # use LLM-generated summary
        summary_index = SummaryIndex.from_documents(
            [docs_dict[title]], callback_manager=callback_manager
        )
        summarizer = summary_index.as_query_engine(
            response_mode="tree_summarize", llm=llm
        )
        response = await summarizer.aquery(
            f"Give me a summary of {title}"
        )
        article_summary = response.response
        Path("summaries").mkdir(exist_ok=True)
        with open(out_path, "w") as fp:
            fp.write(article_summary)
    else:
        with open(out_path, "r") as fp:
            article_summary = fp.read()
    print(f"**Summary for {title}: {article_summary}")
    node = IndexNode(text=article_summary, index_id=title)
    nodes.append(node)Được hỗ trợ bởi

**********
Trace: index_construction
**********
**Summary for How to Do Great Work: The essence of doing great work revolves around a few key principles. First, it's crucial to choose a field that aligns with your natural aptitudes and deep interests, as this will drive your motivation and creativity. Engaging in your own projects and maintaining a sense of excited curiosity are vital for discovering new ideas and making significant contributions.
Learning enough to reach the frontiers of knowledge in your chosen field allows you to identify gaps and explore them, often leading to innovative breakthroughs. Hard work is essential, but it should be fueled by genuine interest rather than mere diligence. Consistency and the willingness to embrace challenges, including the risk of failure, are important for growth and discovery.
Collaboration with high-quality colleagues can enhance your work, as they can provide insights and encouragement. Maintaining morale is also crucial; a positive mindset can help you navigate setbacks and keep you focused on your goals.
Ultimately, curiosity serves as the driving force behind great work, guiding you through the process of exploration and discovery. By nurturing your curiosity and being open to new experiences, you can uncover unique opportunities and make meaningful contributions in your field.
**********
Trace: index_construction
**********
**Summary for Having Kids: The piece reflects on the author's transformation in perspective regarding parenthood. Initially apprehensive about having children, viewing parents as uncool and burdensome, the author experiences a profound shift after becoming a parent. The arrival of their first child triggers protective instincts and a newfound appreciation for children, leading to genuine joy in parenting moments that were previously overlooked. 
The author acknowledges the challenges of parenthood, such as reduced productivity and ambition, as well as the necessity of adapting to a child's schedule. Despite these challenges, the author finds that the happiness and meaningful moments shared with children far outweigh the difficulties. The narrative emphasizes that while parenting can be demanding, it also brings unexpected joy and fulfillment, ultimately leading to a richer life experience.
**********
Trace: index_construction
**********
**Summary for How to Lose Time and Money: The piece discusses the author's reflections on wealth and time management after selling a startup. It emphasizes that losing wealth often stems from poor investments rather than excessive spending, as the latter triggers alarms in our minds. The author highlights the need to develop new awareness to avoid bad investments, which can be less obvious than overspending on luxuries. Similarly, when it comes to time, the most significant loss occurs not through leisure activities but through engaging in unproductive work that feels legitimate, like managing emails. The author argues that modern complexities require us to recognize and avoid these deceptive traps that mimic productive behavior but ultimately lead to wasted time.Được hỗ trợ bởi

Như bạn thấy, hiện chúng ta có ba node, mỗi node đại diện cho một bản tóm tắt của một tài liệu. Ngoài ra, chúng ta có vector_retrievers, nơi lưu các vector của từng đoạn cho mỗi tài liệu.

print(nodes)
print('------'
print(vector_retrievers)Được hỗ trợ bởi

[IndexNode(id_='406d9927-c9e2-486f-9fc5-111efefc1649', embedding=None, metadata={}, excluded_embed_metadata_keys=[], excluded_llm_metadata_keys=[], relationships={}, text="The essence of doing great work revolves around a few key principles. First, it's crucial to choose a field that aligns with your natural aptitudes and deep interests, as this will drive your motivation and creativity. Engaging in your own projects and maintaining a sense of excited curiosity are vital for discovering new ideas and making significant contributions.\\n\\nLearning enough to reach the frontiers of knowledge in your chosen field allows you to identify gaps and explore them, often leading to innovative breakthroughs. Hard work is essential, but it should be fueled by genuine interest rather than mere diligence. Consistency and the willingness to embrace challenges, including the risk of failure, are important for growth and discovery.\\n\\nCollaboration with high-quality colleagues can enhance your work, as they can provide insights and encouragement. Maintaining morale is also crucial; a positive mindset can help you navigate setbacks and keep you focused on your goals.\\n\\nUltimately, curiosity serves as the driving force behind great work, guiding you through the process of exploration and discovery. By nurturing your curiosity and being open to new experiences, you can uncover unique opportunities and make meaningful contributions in your field.", mimetype='text/plain', start_char_idx=None, end_char_idx=None, text_template='{metadata_str}\\n\\n{content}', metadata_template='{key}: {value}', metadata_seperator='\\n', index_id='How to Do Great Work', obj=None),
 IndexNode(id_='8007fdd2-6617-4a76-95d7-79efef0700e7', embedding=None, metadata={}, excluded_embed_metadata_keys=[], excluded_llm_metadata_keys=[], relationships={}, text="The piece reflects on the author's transformation in perspective regarding parenthood. Initially apprehensive about having children, viewing parents as uncool and burdensome, the author experiences a profound shift after becoming a parent. The arrival of their first child triggers protective instincts and a newfound appreciation for children, leading to genuine joy in parenting moments that were previously overlooked. \\n\\nThe author acknowledges the challenges of parenthood, such as reduced productivity and ambition, as well as the necessity of adapting to a child's schedule. Despite these challenges, the author finds that the happiness and meaningful moments shared with children far outweigh the difficulties. The narrative emphasizes that while parenting can be demanding, it also brings unexpected joy and fulfillment, ultimately leading to a richer life experience.", mimetype='text/plain', start_char_idx=None, end_char_idx=None, text_template='{metadata_str}\\n\\n{content}', metadata_template='{key}: {value}', metadata_seperator='\\n', index_id='Having Kids', obj=None),
 IndexNode(id_='7e4dd169-eb28-4b2f-8a1a-ca1c5b85ac30', embedding=None, metadata={}, excluded_embed_metadata_keys=[], excluded_llm_metadata_keys=[], relationships={}, text="The piece discusses the author's reflections on wealth and time management after selling a startup. It emphasizes that losing wealth often stems from poor investments rather than excessive spending, as the latter triggers alarms in our minds. The author highlights the need to develop new awareness to avoid bad investments, which can be less obvious than overspending on luxuries. Similarly, when it comes to time, the most significant loss occurs not through leisure activities but through engaging in unproductive work that feels legitimate, like managing emails. The author argues that modern complexities require us to recognize and avoid these deceptive traps that mimic productive behavior but ultimately lead to wasted time.", mimetype='text/plain', start_char_idx=None, end_char_idx=None, text_template='{metadata_str}\\n\\n{content}', metadata_template='{key}: {value}', metadata_seperator='\\n', index_id='How to Lose Time and Money', obj=None)]
 ------
 {'How to Do Great Work': <llama_index.core.indices.vector_store.retrievers.retriever.VectorIndexRetriever at 0x330afeeb0>,
 'Having Kids': <llama_index.core.indices.vector_store.retrievers.retriever.VectorIndexRetriever at 0x33129c7c0>,
 'How to Lose Time and Money': <llama_index.core.indices.vector_store.retrievers.retriever.VectorIndexRetriever at 0x32e8929a0>}Được hỗ trợ bởi

Bước 4: Xây dựng chỉ mục vector cấp cao

Khi đã có các bản tóm tắt (nodes), chúng ta có thể tạo chỉ mục vector cấp cao và bộ truy xuất (top_vector_retriever). Chỉ mục này dùng các bản tóm tắt để khởi động quy trình truy xuất. Nó giúp tìm các bản tóm tắt liên quan nhất trước khi đi vào các đoạn chi tiết của tài liệu.

# Build top-level vector index from summary nodes
top_vector_index = VectorStoreIndex(
    nodes, transformations=[splitter], callback_manager=callback_manager
)

# Set up a retriever for the top-level summaries
top_vector_retriever = top_vector_index.as_retriever(similarity_top_k=1)
top_vector_retrieverĐược hỗ trợ bởi

<llama_index.core.indices.vector_store.retrievers.retriever.VectorIndexRetriever at 0x32db715b0>Được hỗ trợ bởi

Bước 5: Thiết lập truy xuất đệ quy

Khi đã có bộ truy xuất cấp cao và bộ truy xuất cho từng tài liệu, chúng ta có thể thiết lập bộ truy xuất đệ quy. Thiết lập này cho phép hệ thống lấy các bản tóm tắt liên quan trước, rồi đi sâu vào các đoạn tài liệu cụ thể dựa trên mức độ liên quan.

from llama_index.core.retrievers import RecursiveRetriever

# Combine top-level retriever with individual document retrievers
recursive_retriever = RecursiveRetriever(
    "vector",
    retriever_dict={"vector": top_vector_retriever, **vector_retrievers},
    verbose=True,
)Được hỗ trợ bởi

Bước 6: Chạy truy vấn truy xuất đệ quy

Cuối cùng, chúng ta sẵn sàng dùng bộ truy xuất đệ quy để chạy một số truy vấn mẫu.

# Run recursive retriever on sample queries
result = recursive_retriever.retrieve("should I have kids?")
for res in result:
    print(res.node.get_content())Được hỗ trợ bởi

Retrieving with query id None: should I have kids?
Retrieved node with id, entering: Having Kids
Retrieving with query id Having Kids: should I have kids?
Retrieving text node: Do you have so little to spare?
And while having kids may be warping my present judgement, it hasn't overwritten my memory. I remember perfectly well what life was like before. Well enough to miss some things a lot, like the ability to take off for some other country at a moment's notice. That was so great. Why did I never do that?
See what I did there? The fact is, most of the freedom I had before kids, I never used. I paid for it in loneliness, but I never used it.
I had plenty of happy times before I had kids. But if I count up happy moments, not just potential happiness but actual happy moments, there are more after kids than before. Now I practically have it on tap, almost any bedtime.
People's experiences as parents vary a lot, and I know I've been lucky. But I think the worries I had before having kids must be pretty common, and judging by other parents' faces when they see their kids, so must the happiness that kids bring.
Retrieving text node: December 2019
Before I had kids, I was afraid of having kids. Up to that point I felt about kids the way the young Augustine felt about living virtuously. I'd have been sad to think I'd never have children. But did I want them now? No.
If I had kids, I'd become a parent, and parents, as I'd known since I was a kid, were uncool. They were dull and responsible and had no fun. And while it's not surprising that kids would believe that, to be honest I hadn't seen much as an adult to change my mind. Whenever I'd noticed parents with kids, the kids seemed to be terrors, and the parents pathetic harried creatures, even when they prevailed.
When people had babies, I congratulated them enthusiastically, because that seemed to be what one did. But I didn't feel it at all. "Better you than me," I was thinking.
Now when people have babies I congratulate them enthusiastically and I mean it. Especially the first one. I feel like they just got the best gift in the world.
Retrieving text node: Which meant I had to finish or I'd be taking away their trip to Africa. Maybe if I'm really lucky such tricks could put me net ahead. But the wind is there, no question.
On the other hand, what kind of wimpy ambition do you have if it won't survive having kids? Do you have so little to spare?
And while having kids may be warping my present judgement, it hasn't overwritten my memory. I remember perfectly well what life was like before. Well enough to miss some things a lot, like the ability to take off for some other country at a moment's notice. That was so great. Why did I never do that?
See what I did there? The fact is, most of the freedom I had before kids, I never used. I paid for it in loneliness, but I never used it.
I had plenty of happy times before I had kids. But if I count up happy moments, not just potential happiness but actual happy moments, there are more after kids than before. Now I practically have it on tap, almost any bedtime.Được hỗ trợ bởi

result = recursive_retriever.retrieve("How to buy more time?")
for res in result:
    print(res.node.get_content())Được hỗ trợ bởi

Retrieving with query id None: How to buy more time?
Retrieved node with id, entering: How to Lose Time and Money
Retrieving with query id How to Lose Time and Money: How to buy more time?
Retrieving text node: Which is why people trying to sell you expensive things say "it's an investment."
The solution is to develop new alarms. This can be a tricky business, because while the alarms that prevent you from overspending are so basic that they may even be in our DNA, the ones that prevent you from making bad investments have to be learned, and are sometimes fairly counterintuitive.
A few days ago I realized something surprising: the situation with time is much the same as with money. The most dangerous way to lose time is not to spend it having fun, but to spend it doing fake work. When you spend time having fun, you know you're being self-indulgent. Alarms start to go off fairly quickly. If I woke up one morning and sat down on the sofa and watched TV all day, I'd feel like something was terribly wrong. Just thinking about it makes me wince. I'd start to feel uncomfortable after sitting on a sofa watching TV for 2 hours, let alone a whole day.
Retrieving text node: The solution is to develop new alarms. This can be a tricky business, because while the alarms that prevent you from overspending are so basic that they may even be in our DNA, the ones that prevent you from making bad investments have to be learned, and are sometimes fairly counterintuitive.
A few days ago I realized something surprising: the situation with time is much the same as with money. The most dangerous way to lose time is not to spend it having fun, but to spend it doing fake work. When you spend time having fun, you know you're being self-indulgent. Alarms start to go off fairly quickly. If I woke up one morning and sat down on the sofa and watched TV all day, I'd feel like something was terribly wrong. Just thinking about it makes me wince. I'd start to feel uncomfortable after sitting on a sofa watching TV for 2 hours, let alone a whole day.
And yet I've definitely had days when I might as well have sat in front of a TV all day — days at the end of which, if I asked myself what I got done that day, the answer would have been: basically, nothing.
Retrieving text node: Investing bypasses those alarms. You're not spending the money; you're just moving it from one asset to another. Which is why people trying to sell you expensive things say "it's an investment."
The solution is to develop new alarms. This can be a tricky business, because while the alarms that prevent you from overspending are so basic that they may even be in our DNA, the ones that prevent you from making bad investments have to be learned, and are sometimes fairly counterintuitive.
A few days ago I realized something surprising: the situation with time is much the same as with money. The most dangerous way to lose time is not to spend it having fun, but to spend it doing fake work. When you spend time having fun, you know you're being self-indulgent. Alarms start to go off fairly quickly. If I woke up one morning and sat down on the sofa and watched TV all day, I'd feel like something was terribly wrong. Just thinking about it makes me wince.Được hỗ trợ bởi

Kết luận

Bằng cách sử dụng tóm tắt và phân cấp tài liệu, truy xuất đệ quy giúp các đoạn được truy xuất phù hợp hơn, ngay cả khi xử lý các tập dữ liệu lớn. Với các tổ chức xử lý khối lượng dữ liệu lớn, truy xuất đệ quy là một phương pháp đáng tin cậy để xây dựng hệ thống truy xuất chính xác hơn.

Để tìm hiểu thêm về các kỹ thuật RAG, tôi gợi ý các bài blog sau:

• Triển khai Corrective RAG (CRAG) với LangGraph
• RAG với Llama 3.1 8B, Ollama và Langchain
• RankGPT như một tác nhân xếp hạng lại cho RAG
• Sử dụng Knowledge Graph để triển khai ứng dụng RAG
• Triển khai Speculative RAG với Transformers