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pgvector: Embeddings and vector similarity

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

Learn more about Supabase's AI & Vector offering.

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 for retrieval augmented generation.

Usage

Enable the extension

  1. Go to the Database page in the Dashboard.
  2. Click on Extensions in the sidebar.
  3. Search for "vector" and enable the extension.

Usage

Create a table to store vectors


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create table posts (
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id serial primary key,
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title text not null,
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body text not null,
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embedding vector(384)
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);

Storing a vector / embedding

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


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import { pipeline } from '@xenova/transformers'
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const generateEmbedding = await pipeline('feature-extraction', 'Supabase/gte-small')
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const title = 'First post!'
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const body = 'Hello world!'
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// Generate a vector using Transformers.js
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const output = await generateEmbedding(body, {
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pooling: 'mean',
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normalize: true,
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})
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// Extract the embedding output
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const embedding = Array.from(output.data)
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// Store the vector in Postgres
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const { data, error } = await supabase.from('posts').insert({
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title,
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body,
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embedding,
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})

More pgvector and Supabase resources