Support hybrid search in both rust and node SDKs.
- Adds a new rerankers package to rust LanceDB, with the implementation
of the default RRF reranker
- Adds a new hybrid package to lancedb, with some helper methods related
to hybrid search such as normalizing scores and converting score column
to rank columns
- Adds capability to LanceDB VectorQuery to perform hybrid search if it
has both a nearest vector and full text search parameters.
- Adds wrappers for reranker implementations to nodejs SDK.
Additional rerankers will be added in followup PRs
https://github.com/lancedb/lancedb/issues/1921
---
Notes about how the rust rerankers are wrapped for calling from JS:
I wanted to keep the core reranker logic, and the invocation of the
reranker by the query code, in Rust. This aligns with the philosophy of
the new node SDK where it's just a thin wrapper around Rust. However, I
also wanted to have support for users who want to add custom rerankers
written in Javascript.
When we add a reranker to the query from Javascript, it adds a special
Rust reranker that has a callback to the Javascript code (which could
then turn around and call an underlying Rust reranker implementation if
desired). This adds a bit of complexity, but overall I think it moves us
in the right direction of having the majority of the query logic in the
underlying Rust SDK while keeping the option open to support custom
Javascript Rerankers.
