pgvector support for Lua

Supports pgmoon

Run:

luarocks install pgvector

And follow the instructions for your database library:

• pgmoon

Or check out some examples:

• Embeddings with OpenAI
• Binary embeddings with Cohere
• Hybrid search with Ollama (Reciprocal Rank Fusion)
• Sparse search with Text Embeddings Inference

Require the library

local pgvector = require("pgvector")

Enable the extension

pg:query("CREATE EXTENSION IF NOT EXISTS vector")

Create a table

pg:query("CREATE TABLE items (id bigserial PRIMARY KEY, embedding vector(3))")

Insert a vector

local embedding = pgvector.new({1, 1, 1})
pg:query("INSERT INTO items (embedding) VALUES ($1)", embedding)

Get the nearest neighbors

local embedding = pgvector.new({1, 1, 1})
local res = pg:query("SELECT * FROM items ORDER BY embedding <-> $1 LIMIT 5", embedding)
for i, row in ipairs(res) do
  print(row["id"])
end

Add an approximate index

pg:query("CREATE INDEX ON items USING hnsw (embedding vector_l2_ops)")
-- or
pg:query("CREATE INDEX ON items USING ivfflat (embedding vector_l2_ops) WITH (lists = 100)")

Use vector_ip_ops for inner product and vector_cosine_ops for cosine distance

See a full example

Create a half vector from a table

local vec = pgvector.halfvec({1, 2, 3})

Create a sparse vector from a table of non-zero elements

local elements = {[1] = 1, [3] = 2, [5] = 3}
local vec = pgvector.sparsevec(elements, 6)

Get the number of dimensions

vec["dim"]

Get the non-zero elements

vec["elements"]

View the changelog

Everyone is encouraged to help improve this project. Here are a few ways you can help:

• Report bugs
• Fix bugs and submit pull requests
• Write, clarify, or fix documentation
• Suggest or add new features

To get started with development:

git clone https://github.com/pgvector/pgvector-lua.git
cd pgvector-lua
createdb pgvector_lua_test
luarocks install pgmoon
luarocks install luasocket
lua test/pgvector.lua

To run an example:

createdb pgvector_example
luarocks install luasec
luarocks install lua-cjson
lua examples/openai/example.lua