proposal: Add RecentnessRanker component

[elundaeva]

This proposal is for adding RecentnessRanker to Haystack. The ranker will allow to have retrieved documents sorted not only by relevance (default) but also with recency factored in. Here's the link to the code for this reranker: https://github.com/deepset-ai/haystack/pull/5301/files. The proposal contains an example pipeline setup with RecentnessRanker as well as some example use cases where sorting by recency can be important (e.g. when setting up QA on news content).

[ZanSara]

Hey @elundaeva! I'll remove the proposal tag, as it has a different meaning and doesn't apply here 🙂

[sjrl]

Hey @ZanSara just to let you know, @elundaeva will be splitting this up into two separate PRs, one for the proposal and one for a draft PR of the code changes.

[bogdankostic]

Thanks @elundaeva, I think this would be a great addition to Haystack! Before approving this proposal, I would like the Detailed design section to be more comprehensive.

[bogdankostic]

Thanks for making the requested changes, @elundaeva! This looks good to me now!

According to our proposal process, the proposal needs the approval from three core contributors to move to the final comment phase. I'll share it with the rest of the core team :)

[anakin87]

LGTM!
Thx @elundaeva...

[silvanocerza]

Looks nice to me but I have some critiques.

I think we should remove the links that point to private repos, the community won't be able to access them and that's a bum. We already have #5301 to show the code and that's fine.

I saw the relative PR mentions a paper in regards of the k value used for the reciprocal rank fusion method, can we maybe link it here in the proposal?

Also would love if the PR description was formatted a bit more, deleting the template and briefly explaining the proposal would have been fine. 💙

[silvanocerza]

Awesome! 🚀

[elundaeva]

Thank you everyone for the feedback, the proposal is now merged 🙂 💯