97abe337ba
this is a simple fix for #2219 i also added some documentation for this environment variable
1.3 KiB
PGVector
This page covers how to use the Postgres PGVector ecosystem within LangChain It is broken into two parts: installation and setup, and then references to specific PGVector wrappers.
Installation
- Install the Python package with
pip install pgvector
Setup
-
The first step is to create a database with the
pgvectorextension installed.Follow the steps at PGVector Installation Steps to install the database and the extension. The docker image is the easiest way to get started.
Wrappers
VectorStore
There exists a wrapper around Postgres vector databases, allowing you to use it as a vectorstore, whether for semantic search or example selection.
To import this vectorstore:
from langchain.vectorstores.pgvector import PGVector
PGVector embedding size is not autodetected. If you are using ChatGPT or any other embedding with 1536 dimensions
default is fine. If you are going to use for example HuggingFaceEmbeddings you need to set the environment variable named PGVECTOR_VECTOR_SIZE
to the needed value, In case of HuggingFaceEmbeddings is would be: PGVECTOR_VECTOR_SIZE=768
Usage
For a more detailed walkthrough of the PGVector Wrapper, see this notebook