What is parent-child (small-to-big) retrieval, and why does it improve RAG?
Small chunks match precisely but starve the LLM of context; big chunks carry context but match badly. Parent-child retrieval declines to choose. The signal is separating what you match on from what you feed the model.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
Small chunks match precisely but starve the LLM of context; big chunks carry context but match badly. Parent-child retrieval declines to choose. The signal is separating what you match on from what you feed the model.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
