Topic · 3 posts
Retrieval-Augmented Generation
Chunking, embeddings, similarity, citations, and the failure modes that look like model problems but are retrieval problems.
- 5 min
Hybrid retrieval made my results worse
Everyone recommends fusing lexical and dense retrieval, then reranking. I measured it on a hand-labelled set and the default recommendation finished third of six configurations — behind dense retrieval on its own.
- 6 min
Row-level security is a schema decision, not a code-review convention
Four tables, four policies, and one keyword in a Postgres function that decides whether any of it works. Verified against a second account rather than assumed — because a tenancy bug is not the kind you find by reading.
- 6 min
Deleting the similarity threshold is what made retrieval work
A fixed cosine cutoff was silently discarding the chunks that held the answer. Removing it entirely — and letting the prompt judge relevance instead — fixed a bug I had spent a week blaming on the model.