langchain-shannonbase

A LangChain VectorStore for MySQL 9's native VECTOR type — so you can do RAG on a database you already run.

Works with ShannonBase (the open-source MySQL-for-AI), self-hosted MySQL 9, and MySQL HeatWave — they all share the same VECTOR / STRING_TO_VECTOR / DISTANCE surface.

Why this exists

If your data already lives in MySQL, your options for LangChain vector search were thin: the only MySQL VectorStore is locked to Google Cloud SQL, and ShannonBase's LangChain integration was on its wishlist but unbuilt. This fills that gap — a plain, self-hostable adapter that plugs MySQL 9 into the LangChain ecosystem, no separate vector database required.

Install

pip install "langchain-shannonbase[mysql]"

Use

from langchain_openai import OpenAIEmbeddings
from langchain_shannonbase import ShannonBaseVectorStore

store = ShannonBaseVectorStore(
    embedding=OpenAIEmbeddings(model="text-embedding-3-small"),
    table="documents",
    host="127.0.0.1", port=3306, user="root", password="", database="rag",
)

store.add_texts(
    ["Refunds are accepted within 30 days.", "Free shipping over $50."],
    metadatas=[{"topic": "refunds"}, {"topic": "shipping"}],
)

# It's a normal LangChain vector store — use it directly or as a retriever:
docs = store.similarity_search("return policy?", k=2)
retriever = store.as_retriever(search_kwargs={"k": 3})

Because it implements LangChain's VectorStore interface, it drops into any LangChain chain, retriever, or RAG pipeline unchanged.

How it works

Under the hood it uses MySQL 9's native vector features — no extensions:

CREATE TABLE documents (
  id VARCHAR(36) PRIMARY KEY,
  content TEXT, metadata JSON,
  embedding VECTOR(1536)
);
-- inserts go through STRING_TO_VECTOR('[...]')
-- search: ORDER BY DISTANCE(embedding, STRING_TO_VECTOR('[...]'), 'COSINE')

Similarity search reads back the nearest rows by cosine distance and returns them as LangChain Documents with a score (1 - distance).

API

Testing

The core logic is unit-tested offline via an in-memory backend (no database needed — pytest). A live round-trip test runs against a real instance when you set the connection env vars:

export SB_HOST=127.0.0.1 SB_USER=root SB_PASSWORD=... SB_DATABASE=test
pytest tests/test_integration.py

Local dev tip: run ShannonBase to get MySQL-9 vector features without a HeatWave subscription.

Requirements

• Python 3.9+
• A MySQL-9-compatible database with the VECTOR type (ShannonBase, MySQL 9, or HeatWave)
• mysql-connector-python (installed via the [mysql] extra)

License

MIT © Apoorva Verma