RAG Interview Questions, issue 22, Jul 26, 2026
The Untyped Edge Paradox
ML Engineer interview at Google DeepMind, and the interviewer asks:
“Your GraphRAG system uses a generic related_to edge to catch messy connections. Recall jumped. Six months later, retrieval quality is quietly rotting. What went wrong?”
Don’t say: “The graph got too big, we need to prune it.”
The hidden trap where connecting more nodes actually destroys traversal precision, and why a single generic edge can turn your structured knowledge graph into a semantic landfill.
The full answer, with the mechanism and the arithmetic, is for paid subscribers on Substack.