PGVector#

PGVector is an open-source vector similarity search for Postgres

It supports:

  • exact and approximate nearest neighbor search

  • L2 distance, inner product, and cosine distance

This notebook shows how to use the Postgres vector database (PGVector).

See the installation instruction.

# Pip install necessary package
!pip install pgvector
!pip install openai
!pip install psycopg2-binary
!pip install tiktoken

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We want to use OpenAIEmbeddings so we have to get the OpenAI API Key.

import os
import getpass

os.environ['OPENAI_API_KEY'] = getpass.getpass('OpenAI API Key:')

OpenAI API Key:路路路路路路路路

## Loading Environment Variables
from typing import List, Tuple
from dotenv import load_dotenv
load_dotenv()

False

from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.text_splitter import CharacterTextSplitter
from langchain.vectorstores.pgvector import PGVector
from langchain.document_loaders import TextLoader
from langchain.docstore.document import Document

loader = TextLoader('../../../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()

## PGVector needs the connection string to the database.
## We will load it from the environment variables.
import os
CONNECTION_STRING = PGVector.connection_string_from_db_params(
    driver=os.environ.get("PGVECTOR_DRIVER", "psycopg2"),
    host=os.environ.get("PGVECTOR_HOST", "localhost"),
    port=int(os.environ.get("PGVECTOR_PORT", "5432")),
    database=os.environ.get("PGVECTOR_DATABASE", "postgres"),
    user=os.environ.get("PGVECTOR_USER", "postgres"),
    password=os.environ.get("PGVECTOR_PASSWORD", "postgres"),
)


## Example
# postgresql+psycopg2://username:password@localhost:5432/database_name

# ## PGVector needs the connection string to the database.
# ## We will load it from the environment variables.
# import os
# CONNECTION_STRING = PGVector.connection_string_from_db_params(
#     driver=os.environ.get("PGVECTOR_DRIVER", "psycopg2"),
#     host=os.environ.get("PGVECTOR_HOST", "localhost"),
#     port=int(os.environ.get("PGVECTOR_PORT", "5432")),
#     database=os.environ.get("PGVECTOR_DATABASE", "rd-embeddings"),
#     user=os.environ.get("PGVECTOR_USER", "admin"),
#     password=os.environ.get("PGVECTOR_PASSWORD", "password"),
# )


# ## Example
# # postgresql+psycopg2://username:password@localhost:5432/database_name

Similarity search with score#

Similarity Search with Euclidean Distance (Default)#

# The PGVector Module will try to create a table with the name of the collection. So, make sure that the collection name is unique and the user has the 
# permission to create a table.

db = PGVector.from_documents(
    embedding=embeddings,
    documents=docs,
    collection_name="state_of_the_union",
    connection_string=CONNECTION_STRING,
)

query = "What did the president say about Ketanji Brown Jackson"
docs_with_score: List[Tuple[Document, float]] = db.similarity_search_with_score(query)

for doc, score in docs_with_score:
    print("-" * 80)
    print("Score: ", score)
    print(doc.page_content)
    print("-" * 80)

--------------------------------------------------------------------------------
Score:  0.6076804864602984
Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you鈥檙e at it, pass the Disclose Act so Americans can know who is funding our elections. 

Tonight, I鈥檇 like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer鈥攁n 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鈥檚 top legal minds, who will continue Justice Breyer鈥檚 legacy of excellence.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Score:  0.6076804864602984
Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you鈥檙e at it, pass the Disclose Act so Americans can know who is funding our elections. 

Tonight, I鈥檇 like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer鈥攁n 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鈥檚 top legal minds, who will continue Justice Breyer鈥檚 legacy of excellence.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Score:  0.659062774389974
A former top litigator in private practice. A former federal public defender. And from a family of public school educators and police officers. A consensus builder. Since she鈥檚 been nominated, she鈥檚 received a broad range of support鈥攆rom the Fraternal Order of Police to former judges appointed by Democrats and Republicans. 

And if we are to advance liberty and justice, we need to secure the Border and fix the immigration system. 

We can do both. At our border, we鈥檝e installed new technology like cutting-edge scanners to better detect drug smuggling.  

We鈥檝e set up joint patrols with Mexico and Guatemala to catch more human traffickers.  

We鈥檙e putting in place dedicated immigration judges so families fleeing persecution and violence can have their cases heard faster. 

We鈥檙e securing commitments and supporting partners in South and Central America to host more refugees and secure their own borders.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Score:  0.659062774389974
A former top litigator in private practice. A former federal public defender. And from a family of public school educators and police officers. A consensus builder. Since she鈥檚 been nominated, she鈥檚 received a broad range of support鈥攆rom the Fraternal Order of Police to former judges appointed by Democrats and Republicans. 

And if we are to advance liberty and justice, we need to secure the Border and fix the immigration system. 

We can do both. At our border, we鈥檝e installed new technology like cutting-edge scanners to better detect drug smuggling.  

We鈥檝e set up joint patrols with Mexico and Guatemala to catch more human traffickers.  

We鈥檙e putting in place dedicated immigration judges so families fleeing persecution and violence can have their cases heard faster. 

We鈥檙e securing commitments and supporting partners in South and Central America to host more refugees and secure their own borders.
--------------------------------------------------------------------------------

Working with vectorstore in PG#

Uploading a vectorstore in PG#

data=docs
api_key=os.environ['OPENAI_API_KEY']
db = PGVector.from_documents(
    documents=docs,
    embedding=embeddings,
    collection_name=collection_name,
    connection_string=connection_string,
    distance_strategy=DistanceStrategy.COSINE,
    openai_api_key=api_key,
    pre_delete_collection=False 
)

Retrieving a vectorstore in PG#

connection_string = CONNECTION_STRING 
embedding=embeddings
collection_name="state_of_the_union"
from langchain.vectorstores.pgvector import DistanceStrategy
store = PGVector(
    connection_string=connection_string, 
    embedding_function=embedding, 
    collection_name=collection_name,
    distance_strategy=DistanceStrategy.COSINE
)

retriever = store.as_retriever()

print(retriever)

vectorstore=<langchain.vectorstores.pgvector.PGVector object at 0x7fe9a1b1c670> search_type='similarity' search_kwargs={}

# When we have an existing PG VEctor 
DEFAULT_DISTANCE_STRATEGY = DistanceStrategy.EUCLIDEAN
db1 = PGVector.from_existing_index(
    embedding=embeddings,
    collection_name="state_of_the_union",
    distance_strategy=DEFAULT_DISTANCE_STRATEGY,
    pre_delete_collection = False,
    connection_string=CONNECTION_STRING,
)

query = "What did the president say about Ketanji Brown Jackson"
docs_with_score: List[Tuple[Document, float]] = db1.similarity_search_with_score(query)
print(docs_with_score)

[(Document(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鈥檙e at it, pass the Disclose Act so Americans can know who is funding our elections. \n\nTonight, I鈥檇 like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer鈥攁n Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. \n\nOne of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court. \n\nAnd I did that 4 days ago, when I nominated Circuit Court of Appeals Judge Ketanji Brown Jackson. One of our nation鈥檚 top legal minds, who will continue Justice Breyer鈥檚 legacy of excellence.', metadata={'source': '../../../state_of_the_union.txt'}), 0.6075870262188066), (Document(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鈥檙e at it, pass the Disclose Act so Americans can know who is funding our elections. \n\nTonight, I鈥檇 like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer鈥攁n Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. \n\nOne of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court. \n\nAnd I did that 4 days ago, when I nominated Circuit Court of Appeals Judge Ketanji Brown Jackson. One of our nation鈥檚 top legal minds, who will continue Justice Breyer鈥檚 legacy of excellence.', metadata={'source': '../../../state_of_the_union.txt'}), 0.6075870262188066), (Document(page_content='A former top litigator in private practice. A former federal public defender. And from a family of public school educators and police officers. A consensus builder. Since she鈥檚 been nominated, she鈥檚 received a broad range of support鈥攆rom the Fraternal Order of Police to former judges appointed by Democrats and Republicans. \n\nAnd if we are to advance liberty and justice, we need to secure the Border and fix the immigration system. \n\nWe can do both. At our border, we鈥檝e installed new technology like cutting-edge scanners to better detect drug smuggling.  \n\nWe鈥檝e set up joint patrols with Mexico and Guatemala to catch more human traffickers.  \n\nWe鈥檙e putting in place dedicated immigration judges so families fleeing persecution and violence can have their cases heard faster. \n\nWe鈥檙e securing commitments and supporting partners in South and Central America to host more refugees and secure their own borders.', metadata={'source': '../../../state_of_the_union.txt'}), 0.6589478388546668), (Document(page_content='A former top litigator in private practice. A former federal public defender. And from a family of public school educators and police officers. A consensus builder. Since she鈥檚 been nominated, she鈥檚 received a broad range of support鈥攆rom the Fraternal Order of Police to former judges appointed by Democrats and Republicans. \n\nAnd if we are to advance liberty and justice, we need to secure the Border and fix the immigration system. \n\nWe can do both. At our border, we鈥檝e installed new technology like cutting-edge scanners to better detect drug smuggling.  \n\nWe鈥檝e set up joint patrols with Mexico and Guatemala to catch more human traffickers.  \n\nWe鈥檙e putting in place dedicated immigration judges so families fleeing persecution and violence can have their cases heard faster. \n\nWe鈥檙e securing commitments and supporting partners in South and Central America to host more refugees and secure their own borders.', metadata={'source': '../../../state_of_the_union.txt'}), 0.6589478388546668)]

for doc, score in docs_with_score:
    print("-" * 80)
    print("Score: ", score)
    print(doc.page_content)
    print("-" * 80)

--------------------------------------------------------------------------------
Score:  0.6075870262188066
Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you鈥檙e at it, pass the Disclose Act so Americans can know who is funding our elections. 

Tonight, I鈥檇 like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer鈥攁n 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鈥檚 top legal minds, who will continue Justice Breyer鈥檚 legacy of excellence.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Score:  0.6075870262188066
Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you鈥檙e at it, pass the Disclose Act so Americans can know who is funding our elections. 

Tonight, I鈥檇 like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer鈥攁n 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鈥檚 top legal minds, who will continue Justice Breyer鈥檚 legacy of excellence.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Score:  0.6589478388546668
A former top litigator in private practice. A former federal public defender. And from a family of public school educators and police officers. A consensus builder. Since she鈥檚 been nominated, she鈥檚 received a broad range of support鈥攆rom the Fraternal Order of Police to former judges appointed by Democrats and Republicans. 

And if we are to advance liberty and justice, we need to secure the Border and fix the immigration system. 

We can do both. At our border, we鈥檝e installed new technology like cutting-edge scanners to better detect drug smuggling.  

We鈥檝e set up joint patrols with Mexico and Guatemala to catch more human traffickers.  

We鈥檙e putting in place dedicated immigration judges so families fleeing persecution and violence can have their cases heard faster. 

We鈥檙e securing commitments and supporting partners in South and Central America to host more refugees and secure their own borders.
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
Score:  0.6589478388546668
A former top litigator in private practice. A former federal public defender. And from a family of public school educators and police officers. A consensus builder. Since she鈥檚 been nominated, she鈥檚 received a broad range of support鈥攆rom the Fraternal Order of Police to former judges appointed by Democrats and Republicans. 

And if we are to advance liberty and justice, we need to secure the Border and fix the immigration system. 

We can do both. At our border, we鈥檝e installed new technology like cutting-edge scanners to better detect drug smuggling.  

We鈥檝e set up joint patrols with Mexico and Guatemala to catch more human traffickers.  

We鈥檙e putting in place dedicated immigration judges so families fleeing persecution and violence can have their cases heard faster. 

We鈥檙e securing commitments and supporting partners in South and Central America to host more refugees and secure their own borders.
--------------------------------------------------------------------------------