pgvector: Embeddings and vector similarity

pgvector is a PostgreSQL extension for vector similarity search. It can also be used for storing embeddings.

Concepts#

Vector similarity#

Vector similarity refers to a measure of the similarity between two related items. For example, if you have a list of products, you can use vector similarity to find similar products. To do this, you need to convert each product into a "vector" of numbers, using a mathematical model. You can use a similar model for text, images, and other types of data. Once all of these vectors are stored in the database, you can use vector similarity to find similar items.

Embeddings#

This is particularly useful if you're building on top of OpenAI's GPT-3. You can create and store embeddings which match the GPT model you're using.

Usage#

Enable the extension#

Usage#

Create a table to store vectors#

create table posts (
  id serial primary key,
  title text not null,
  body text not null,
  embedding vector(1536)
);

Storing a vector / embedding#

In this example we'll generate a vector using the OpenAI API client, then store it in the database using the Supabase client.

const title = 'First post!'
const body = 'Hello world!'

// Generate a vector using OpenAI
const embeddingResponse = await openai.createEmbedding({
  model: 'text-embedding-ada-002',
  input: body,
})
const [responseData] = embeddingResponse.data.data.

// Store the vector in Postgres
const { data, error } = await supabase.from('posts').insert({
  title,
  body,
  embedding: responseData.embedding,
})

Resources#

• Source code: github.com/pgvector/pgvector