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AnalyticDB for PostgreSQL 是一种大规模并行处理（MPP）数据仓库服务，专为在线分析海量数据而设计。
AnalyticDB for PostgreSQL 基于开源的 Greenplum Database 项目开发，并由 阿里云 进行深度扩展增强。AnalyticDB for PostgreSQL 兼容 ANSI SQL 2003 语法以及 PostgreSQL 和 Oracle 数据库生态系统，同时支持行存储和列存储。AnalyticDB for PostgreSQL 能以高性能离线处理 PB 级数据，并支持高并发在线查询。
使用此集成需要通过 pip install -qU langchain-community 安装 langchain-community。 本 notebook 展示了如何使用 AnalyticDB 向量数据库的相关功能。 运行前，您需要确保 AnalyticDB 实例已正常启动并运行： 
from langchain_community.vectorstores import AnalyticDB
from langchain_openai import OpenAIEmbeddings
from langchain_text_splitters import CharacterTextSplitter
拆分文档并通过调用 OpenAI API 获取嵌入向量 
from langchain_community.document_loaders import TextLoader

loader = TextLoader("../../how_to/state_of_the_union.txt")
documents = loader.load()
text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=0)
docs = text_splitter.split_documents(documents)

embeddings = OpenAIEmbeddings()
通过设置相关环境变量连接 AnalyticDB。 
export PG_HOST={your_analyticdb_hostname}
export PG_PORT={your_analyticdb_port} # Optional, default is 5432
export PG_DATABASE={your_database} # Optional, default is postgres
export PG_USER={database_username}
export PG_PASSWORD={database_password}
然后将嵌入向量和文档存储到 AnalyticDB 
import os

connection_string = AnalyticDB.connection_string_from_db_params(
    driver=os.environ.get("PG_DRIVER", "psycopg2cffi"),
    host=os.environ.get("PG_HOST", "localhost"),
    port=int(os.environ.get("PG_PORT", "5432")),
    database=os.environ.get("PG_DATABASE", "postgres"),
    user=os.environ.get("PG_USER", "postgres"),
    password=os.environ.get("PG_PASSWORD", "postgres"),
)

vector_db = AnalyticDB.from_documents(
    docs,
    embeddings,
    connection_string=connection_string,
)
查询并检索数据 
query = "What did the president say about Ketanji Brown Jackson"
docs = vector_db.similarity_search(query)

print(docs[0].page_content)

Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you’re at it, pass the Disclose Act so Americans can know who is funding our elections.

Tonight, I’d like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service.

One of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court.

And I did that 4 days ago, when I nominated Circuit Court of Appeals Judge Ketanji Brown Jackson. One of our nation’s top legal minds, who will continue Justice Breyer’s legacy of excellence.
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