Exploring Reranking Options for Discourse AI

Oh, I see now, thanks for the explanation, that’s what I was missing.

Btw, I know often there’s reranking in more advances RAG. Is there something like reranking in how Discourse handles is? Do you think adding a reranking step would have any positive effect?

reranking is a work-in-progress.

@Falco / @Roman implemented a basic reranker in discourse:

This is used in semantic search and RAG. However it is quite hidden and not easy to configure.

I think the medium term plan here (which we discussed with @awesomerobot ) was to move from LLM terminology to Models … and maybe do a bit of UI unification so you can define embedding/rerankers and llms in a single interface.

For now we only support a very specific hugging face reranker api.

It certainly improves quality of results.

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Awesome!
So currently this is off by default, and can’t be configured easily on a hosted (pro) plan?

not sure, lets wait for @Falco to answer.

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Hi @Falco
is there any way to enable the reranker for testing or maybe a timeline?

We just deployed a big improvement to the underlying tech that powers semantic search in Discourse in DEV: Re-introduce PG Vector 0.8.0 upgrade by romanrizzi · Pull Request #35233 · discourse/discourse · GitHub.

Can you retry your use case now, it’s already deployed to your site. My expectation is that this will make RAG better without the need for a reranker.

We still want to make the re-ranker widely available, but we are waiting for some upstream changes to land first.

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Thanks Falco!

Will this work only for the semantic search over Discourse topics, or also for RAG documents uploaded to a persona? From my own experience, the AI works quite well with forum topics (i.e. on ask.discourse), but not that well with uploaded docs to a persona (or I haven’t found the best formula yet).

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It affects all uses of embeddings in Discourse, including Related Topics, RAG, Search, Composer category and tag suggestions, etc.

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Hey @tpetrov, did the results improve with the new embeddings model?

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Hey Falco, I’m sorry, I haven’t had time to test extensively, so cannot really say.

I guess there’s no way to sitch between the two to compare?

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Not now, the old and new models were available for a couple of months, but we recently retired the old ones in our hosting.