vectorstores: DuckDB implementation

Hello folks,

I'm working on a personal project, creating a RAG of personal/local notes/documents, and I resolved to use DuckDB as I want the whole thing to be hosted in a single binary running locally using ollama as the sole dependency. DuckDB offers an extension called vss (doc).

I found myself using langchaingo, as it offered a framework to structure my work, very useful for someone that is new to LangChain and this kind of tools.

And so, I'm implementing the VectorStore interface (and spending a bunch of time looking at the code of other implementations, to do it in the most "consistent" way possible).

I currently have the interface implemented, and a few tests running. But I want to add more tests to match the other implementations in here.

Sounds interesting? Once I'm ready, should I go ahead and open a PR? Thoughts?

Thank you Ivan

PS I had originally opened https://github.com/tmc/langchaingo/discussions/1459 but I saw no response. I re-read the contribution guide, and it points are "create an issue to propose improvements", and so here I'm.