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Yellowbrick 是一个弹性的、大规模并行处理（MPP）SQL 数据库，运行在云端和本地，使用 kubernetes 实现扩展、弹性和云可移植性。Yellowbrick 专为应对最大规模和最复杂的业务关键型数据仓库使用场景而设计。Yellowbrick 提供的大规模效率也使其能够作为高性能且可扩展的向量数据库，用于通过 SQL 存储和搜索向量。

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将 yellowbrick 用作 ChatGPT 的向量存储

本教程演示如何创建一个由 ChatGPT 支持的简单聊天机器人，使用 Yellowbrick 作为向量存储以支持检索增强生成（RAG）。您需要：
  1. 一个 Yellowbrick 沙箱账号
  2. 来自 OpenAI 的 API key
本教程分为五个部分。首先，我们将使用 langchain 创建一个基线聊天机器人，在没有向量存储的情况下与 ChatGPT 交互。其次，我们将在 Yellowbrick 中创建一个代表向量存储的嵌入表。第三，我们将加载一系列文档（Yellowbrick 手册的管理章节）。第四，我们将创建这些文档的向量表示并存储在 Yellowbrick 表中。最后，我们将向改进后的聊天机器人发送相同的查询以查看结果。 
# Install all needed libraries
pip install -qU  langchain
pip install -qU  langchain-openai langchain-community
pip install -qU  psycopg2-binary
pip install -qU  tiktoken

​
配置：输入连接 yellowbrick 和 OpenAI API 所用的信息

我们的聊天机器人通过 langchain 库与 ChatGPT 集成，因此您首先需要来自 OpenAI 的 API key： 获取 OpenAI API key 的方法：
  1. 在 platform.openai.com/ 注册
  2. 添加支付方式 - 您不太可能超出免费配额
  3. 创建 API key
您还需要注册 Yellowbrick 沙箱账号时收到的欢迎邮件中的用户名、密码和数据库名称。 以下内容应修改为您的 Yellowbrick 数据库和 OpenAI API Key 的信息 
# Modify these values to match your Yellowbrick Sandbox and OpenAI API Key
YBUSER = "[SANDBOX USER]"
YBPASSWORD = "[SANDBOX PASSWORD]"
YBDATABASE = "[SANDBOX_DATABASE]"
YBHOST = "trialsandbox.sandbox.aws.yellowbrickcloud.com"

OPENAI_API_KEY = "[OPENAI API KEY]"

# Import libraries and setup keys / login info
import os
import pathlib
import re
import sys
import urllib.parse as urlparse
from getpass import getpass

import psycopg2
from IPython.display import Markdown, display
from langchain_classic.chains import LLMChain, RetrievalQAWithSourcesChain
from langchain_community.vectorstores import Yellowbrick
from langchain_core.documents import Document
from langchain_openai import ChatOpenAI, OpenAIEmbeddings
from langchain_text_splitters import RecursiveCharacterTextSplitter

# Establish connection parameters to Yellowbrick.  If you've signed up for Sandbox, fill in the information from your welcome mail here:
yellowbrick_connection_string = (
    f"postgres://{urlparse.quote(YBUSER)}:{YBPASSWORD}@{YBHOST}:5432/{YBDATABASE}"
)

YB_DOC_DATABASE = "sample_data"
YB_DOC_TABLE = "yellowbrick_documentation"
embedding_table = "my_embeddings"

# API Key for OpenAI.  Signup at https://platform.openai.com
os.environ["OPENAI_API_KEY"] = OPENAI_API_KEY

from langchain_core.prompts.chat import (
    ChatPromptTemplate,
    HumanMessagePromptTemplate,
    SystemMessagePromptTemplate,
)

​
第一部分：创建不使用向量存储的 ChatGPT 基线聊天机器人

我们将使用 langchain 查询 ChatGPT。由于没有向量存储，ChatGPT 将没有回答问题的上下文。 
# Set up the chat model and specific prompt
system_template = """If you don't know the answer, Make up your best guess."""
messages = [
    SystemMessagePromptTemplate.from_template(system_template),
    HumanMessagePromptTemplate.from_template("{question}"),
]
prompt = ChatPromptTemplate.from_messages(messages)

chain_type_kwargs = {"prompt": prompt}
llm = ChatOpenAI(
    model_name="gpt-3.5-turbo",  # Modify model_name if you have access to GPT-4
    temperature=0,
    max_tokens=256,
)

chain = LLMChain(
    llm=llm,
    prompt=prompt,
    verbose=False,
)


def print_result_simple(query):
    result = chain(query)
    output_text = f"""### Question:
  {query}
  ### Answer:
  {result["text"]}
    """
    display(Markdown(output_text))


# Use the chain to query
print_result_simple("How many databases can be in a Yellowbrick Instance?")

print_result_simple("What's an easy way to add users in bulk to Yellowbrick?")

​
第二部分：连接 yellowbrick 并创建嵌入表

要将文档嵌入加载到 Yellowbrick 中，您应该创建自己的表来存储它们。注意，表所在的 Yellowbrick 数据库必须是 UTF-8 编码的。 在 UTF-8 数据库中使用以下 schema 创建一个表，提供您选择的表名： 
# Establish a connection to the Yellowbrick database
try:
    conn = psycopg2.connect(yellowbrick_connection_string)
except psycopg2.Error as e:
    print(f"Error connecting to the database: {e}")
    exit(1)

# Create a cursor object using the connection
cursor = conn.cursor()

# Define the SQL statement to create a table
create_table_query = f"""
CREATE TABLE IF NOT EXISTS {embedding_table} (
    doc_id uuid NOT NULL,
    embedding_id smallint NOT NULL,
    embedding double precision NOT NULL
)
DISTRIBUTE ON (doc_id);
truncate table {embedding_table};
"""

# Execute the SQL query to create a table
try:
    cursor.execute(create_table_query)
    print(f"Table '{embedding_table}' created successfully!")
except psycopg2.Error as e:
    print(f"Error creating table: {e}")
    conn.rollback()

# Commit changes and close the cursor and connection
conn.commit()
cursor.close()
conn.close()

​
第三部分：从 yellowbrick 中的现有表提取要索引的文档

从现有 Yellowbrick 表中提取文档路径和内容。我们将在下一步中使用这些文档创建嵌入。 
yellowbrick_doc_connection_string = (
    f"postgres://{urlparse.quote(YBUSER)}:{YBPASSWORD}@{YBHOST}:5432/{YB_DOC_DATABASE}"
)

print(yellowbrick_doc_connection_string)

# Establish a connection to the Yellowbrick database
conn = psycopg2.connect(yellowbrick_doc_connection_string)

# Create a cursor object
cursor = conn.cursor()

# Query to select all documents from the table
query = f"SELECT path, document FROM {YB_DOC_TABLE}"

# Execute the query
cursor.execute(query)

# Fetch all documents
yellowbrick_documents = cursor.fetchall()

print(f"Extracted {len(yellowbrick_documents)} documents successfully!")

# Close the cursor and connection
cursor.close()
conn.close()

​
第四部分：使用文档加载 yellowbrick 向量存储

遍历文档，将其分割成可处理的块，创建嵌入并插入到 Yellowbrick 表中。这大约需要 5 分钟。 
# Split documents into chunks for conversion to embeddings
DOCUMENT_BASE_URL = "https://docs.yellowbrick.com/6.7.1/"  # Actual URL


separator = "\n## "  # This separator assumes Markdown docs from the repo uses ### as logical main header most of the time
chunk_size_limit = 2000
max_chunk_overlap = 200

documents = [
    Document(
        page_content=document[1],
        metadata={"source": DOCUMENT_BASE_URL + document[0].replace(".md", ".html")},
    )
    for document in yellowbrick_documents
]

text_splitter = RecursiveCharacterTextSplitter(
    chunk_size=chunk_size_limit,
    chunk_overlap=max_chunk_overlap,
    separators=[separator, "\nn", "\n", ",", " ", ""],
)
split_docs = text_splitter.split_documents(documents)

docs_text = [doc.page_content for doc in split_docs]

embeddings = OpenAIEmbeddings()
vector_store = Yellowbrick.from_documents(
    documents=split_docs,
    embedding=embeddings,
    connection_string=yellowbrick_connection_string,
    table=embedding_table,
)

print(f"Created vector store with {len(documents)} documents")

​
第五部分：创建使用 yellowbrick 作为向量存储的聊天机器人

接下来，我们将 Yellowbrick 添加为向量存储。该向量存储已填充代表 Yellowbrick 产品文档管理章节的嵌入。 我们将发送与上面相同的查询，以查看改进后的响应。 
system_template = """Use the following pieces of context to answer the users question.
Take note of the sources and include them in the answer in the format: "SOURCES: source1 source2", use "SOURCES" in capital letters regardless of the number of sources.
If you don't know the answer, just say that "I don't know", don't try to make up an answer.
----------------
{summaries}"""
messages = [
    SystemMessagePromptTemplate.from_template(system_template),
    HumanMessagePromptTemplate.from_template("{question}"),
]
prompt = ChatPromptTemplate.from_messages(messages)

vector_store = Yellowbrick(
    OpenAIEmbeddings(),
    yellowbrick_connection_string,
    embedding_table,  # Change the table name to reflect your embeddings
)

chain_type_kwargs = {"prompt": prompt}
llm = ChatOpenAI(
    model_name="gpt-3.5-turbo",  # Modify model_name if you have access to GPT-4
    temperature=0,
    max_tokens=256,
)
chain = RetrievalQAWithSourcesChain.from_chain_type(
    llm=llm,
    chain_type="stuff",
    retriever=vector_store.as_retriever(search_kwargs={"k": 5}),
    return_source_documents=True,
    chain_type_kwargs=chain_type_kwargs,
)


def print_result_sources(query):
    result = chain(query)
    output_text = f"""### Question:
  {query}
  ### Answer:
  {result["answer"]}
  ### Sources:
  {result["sources"]}
  ### All relevant sources:
  {", ".join(list(set([doc.metadata["source"] for doc in result["source_documents"]])))}
    """
    display(Markdown(output_text))


# Use the chain to query

print_result_sources("How many databases can be in a Yellowbrick Instance?")

print_result_sources("Whats an easy way to add users in bulk to Yellowbrick?")

​
第六部分：引入索引以提高性能

Yellowbrick 还支持使用局部敏感哈希（LSH）方法进行索引。这是一种近似最近邻搜索技术，允许以精度为代价来换取相似性搜索时间。该索引引入了两个新的可调参数：
  • 超平面数量，作为参数传递给 create_lsh_index(num_hyperplanes)。文档越多，需要的超平面越多。LSH 是一种降维形式。原始嵌入被转换为低维向量，其中分量数量与超平面数量相同。
  • 汉明距离，一个表示搜索宽度的整数。汉明距离越小，检索速度越快，但精度越低。
以下是如何在我们加载到 Yellowbrick 的嵌入上创建索引。我们还将重新运行之前的聊天会话，但这次检索将使用索引。请注意，对于如此少量的文档，您不会在性能方面看到索引的好处。 
system_template = """Use the following pieces of context to answer the users question.
Take note of the sources and include them in the answer in the format: "SOURCES: source1 source2", use "SOURCES" in capital letters regardless of the number of sources.
If you don't know the answer, just say that "I don't know", don't try to make up an answer.
----------------
{summaries}"""
messages = [
    SystemMessagePromptTemplate.from_template(system_template),
    HumanMessagePromptTemplate.from_template("{question}"),
]
prompt = ChatPromptTemplate.from_messages(messages)

vector_store = Yellowbrick(
    OpenAIEmbeddings(),
    yellowbrick_connection_string,
    embedding_table,  # Change the table name to reflect your embeddings
)

lsh_params = Yellowbrick.IndexParams(
    Yellowbrick.IndexType.LSH, {"num_hyperplanes": 8, "hamming_distance": 2}
)
vector_store.create_index(lsh_params)

chain_type_kwargs = {"prompt": prompt}
llm = ChatOpenAI(
    model_name="gpt-3.5-turbo",  # Modify model_name if you have access to GPT-4
    temperature=0,
    max_tokens=256,
)
chain = RetrievalQAWithSourcesChain.from_chain_type(
    llm=llm,
    chain_type="stuff",
    retriever=vector_store.as_retriever(
        k=5, search_kwargs={"index_params": lsh_params}
    ),
    return_source_documents=True,
    chain_type_kwargs=chain_type_kwargs,
)


def print_result_sources(query):
    result = chain(query)
    output_text = f"""### Question:
  {query}
  ### Answer:
  {result["answer"]}
  ### Sources:
  {result["sources"]}
  ### All relevant sources:
  {", ".join(list(set([doc.metadata["source"] for doc in result["source_documents"]])))}
    """
    display(Markdown(output_text))


# Use the chain to query

print_result_sources("How many databases can be in a Yellowbrick Instance?")

print_result_sources("Whats an easy way to add users in bulk to Yellowbrick?")

​
后续步骤

此代码可以修改以提出不同的问题。您也可以将自己的文档加载到向量存储中。langchain 模块非常灵活，可以解析多种文件（包括 HTML、PDF 等）。 您还可以修改此代码以使用 Huggingface 嵌入模型和 Meta 的 Llama 2 LLM，获得完全私密的聊天体验。
在 GitHub 上编辑此页面 或提交问题。
通过 MCP 将这些文档连接到 Claude、VSCode 等，获取实时答案。