What RAG here is doing is using embeddings and a vector store to identify close pieces of information, for example "in this django project add a textfield" will be very close to documentation in the django docs that say "textfield", and it will then add that to the prompt so the LLM has the relevant docs in its context.
The problem is that you'll need a heuristic to identify at least "potentially anomalous" and even then you'll still have to make sure there's enough context for it to know "is this a normal daily fluctuation".
A multi-step agent is definitely what you want, you could have it build an SQL query itself, for example "was there any high latency requests yesterday?" it may identify it should filter the time, possibly design the query to determine what is "high".
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At the moment I don't think it's well suited to identifying when the "latency is abnormally high". However if you have some other system/human identify heuristics to feed to the LLM, it may then be able to do at least answer the query.