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The RAG Obituary: Killed by agents, buried by context windows

nicolasbustamante.com

161–170 of 185 posts

Re: The RAG Obituary: Killed by agents, buried by context windows

#161
> The agent follows references like a human analyst would. No chunks. No embeddings. No reranking. Just intelligent navigation.

I think this sums it up well. Working with LLMs is already confusing and unpredictable. Adding a convoluted RAG pipeline (unless it is truly necessary because of context size limitations) only makes things worse compared to simply emulating what we would normally do.

Re: The RAG Obituary: Killed by agents, buried by context windows

#164

Earlier quoted context omitted.

Sure, but vector search is the dominant form of RAG, the rest are niche. Saying "RAG doesn’t have to use vectors" is like saying "LLMs don't have to use transformers". Technically true, but irrelevant when 99% of what's in use today does.

How are they niche? The default mode of search for most dedicated RAG apps nowadays is hybrid search that blends classical BM-25 search with some HNSW embedding search. That's already breaking the definition. A search is a search. The architecture doesn't care if it's doing an vector search or a text search or a keyword search or a regex search, it's all the same. Deploying a RAG app means trying different search met…

Most hybrid stacks (BM25 + dense via HNSW/IVF) still rely on embeddings as a first class signal. So in practice the vector side carries recall on paraphrase/synonymy/OOO vocab, while BM25 stabilizes precision on exact term and short doc cases. So my point still stands.

> The architecture doesn't care

The architecture does care because latency, recall shape, and failure modes differ.

I don't know of any serious RAG deployments that don't use vectors. I'm referring to large scale systems, not hobby projects or small sites.

Re: The RAG Obituary: Killed by agents, buried by context windows

#165

I don't get why folks are so dismissive here. If you ever saw Claude Code/Codex use grep, you will find that it constructs complex queries that encompass a whole range of keywords which may not even be present in the original user query. So the 'semantic meaning' isn't actually lost. And nobody is putting an entire enterprise's knowledge base inside the context window. How many enterprise tasks are there that need re…

The article is not making a proper distinction of scale and is probably due to the small scale problem that they solved. What is small scale and 1M documents etc. you will need to use search engine technology. You can definitely do the same agent approach for the large scale problem - we essentially need search, look at the results and issue follow up queries to get documents of interest. All that said, for the types of problem the OP is solving, it might just be better to create a project in Claude/ChatGPT and throw in the files there and get done with it. That approach has been working for over 2 years now and is nothing new.

Re: The RAG Obituary: Killed by agents, buried by context windows

#166
post #94

Agentic search with a handful of basic tools (drawn from BM25, semantic search, tags, SQL, knowledge graph, and a handful of custom retrieval functions) blows the lid off RAG in my experience. The downside is it takes longer. A single “investigation” can easily use 20-30 different function calls. RAG is like a static one-shot version of this and while the results are inferior the process is also a lot faster.

Hey, I’m interested in what you call “agentic search”. Did you roll your own or are you using a set of integrated tools? I’ve used LightRAG and looking to integrate it with OpenWebUI and possibly air weave which was a show HN earlier. My data is highly structured and has references between documents, so I wanted to leverage that structure for better retrieval and reasoning.

Rolled my own in Python.

For graph/tree document representations, it’s common in RAG to use summaries and aggregation. For example, the search yields a match on a chunk, but you want to include context from adjacent chunks — either laterally, in the same document section, or vertically, going up a level to include the title and summary of the parent node. How you integrate and aggregate the surrounding context is up to you. Different RAG systems handle it differently, each with its own trade offs. The point is that the system is static and hardcoded.

The agentic approach is: instead of trying to synthesize and rank/re-rank your search results into a single deliverable, why not leave that to the LLM, which can dynamically traverse your data. For a document tree, I would try exposing the tree structure to the LLM. Return the result with pointers to relevant neighbor nodes, each with a short description. Then the LLM can decide, based on what it finds, to run a new search or explore local nodes.

Re: The RAG Obituary: Killed by agents, buried by context windows

#168
post #135

Earlier quoted context omitted.

Yeah 100% Almost all tool calls would result in rag. Rag is dead just means rolling out your own search and manually injecting results into context is dead (just use tools). It means the chunking techniques are dead.

Chunking is still relevant, because you want your tool calls to return results specific to the needs of the query. If you want to know "how are tartans officially registered" you don't want to feed the entire 554kb wikipedia article on Tartan to your model, using 138,500 tokens, over 35% of gpt-5's context window, with significant monetary and latency cost. You want to feed it just the "Regulation>Registration" subse…

but you could. For that example, you could just use a much cheaper model since it's not that complicated a question, and just pass the entire article. Just use gemini flash for example. Models will only get cheaper and context windows only get bigger

Re: The RAG Obituary: Killed by agents, buried by context windows

#169
post #101

I am so tired of these undifferentiated takes. These types of articles regularly come from people who don't actually build SCALE systems with LLMs. Or, people who want to sell you on a new tech. And the frustrating thing is: They ain't even wrong. Top-K RAG via vector search is not a sufficient solution. It never really was for most interesting use-cases. Of course, take easiest and most structured - in a sense perfe…

I agree. Permit me to rephrase. From this learning adventure https://www.infoq.com/articles/architecting-rag-pipeline/ I came to understand what many now call context rot. If you want quality answers, you still need relevance reranking and filtering no matter how big your context window becomes. Whether that happens in a search that is upfront in a one shot prompt or iteratively in a long session through an agentic system is merely an implementation detail.
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