Support Pinecone's hybrid vectors

[yasyf]

Is your feature request related to a problem? Please describe.
Recently, Pinecone announced support for Sparse-dense embeddings, allowing for hybrid vector search (both semantic and keyword search). However, haystack doesn't currently support these.

Describe the solution you'd like
Native support for sparse-dense vectors!

Describe alternatives you've considered
I've created a small package called haystack-hybrid-embedding which can be installed to support hybrid vectors for now, but it's a hack!

[TuanaCelik]

Hey @yasyf thanks for the issue and linking to your repo. I think we already connected on Twitter. As mentioned there, I propose we create an Integration page for you as a first step, at least until we are ready on our side to implement this into the source code of Haystack :)
I am off next week but I'll create the page and send you a preview when I'm back.
Thank you for your contribution 💙

cc: @bilgeyucel

[Azzeo]

As far as I am aware, Weaviate also supports hybrid search. Would that also be something that would be supported?

[bilgeyucel]

Hi @Azzeo, yes, of course! I can open a separate issue for it. Thank you for letting us know 🙌
Also, I was wondering if you'd like to open a PR for this feature and contribute to Haystack. I am happy to help you throughout the process 😊
Here's the issue btw: #484

[anakin87]

closing in favor of #695