What is parent-child or small-to-big chunking?

Parent-child chunking indexes small chunks for precise retrieval but returns the larger parent chunk to the language model for rich context. At ingest, you split documents into small embedding chunks of 128 to 256 tokens for recall precision, while also storing larger parent chunks of 1024 to 2048 tokens keyed by chunk identifier. At query time, retrieve the best small chunks, look up their parents, and pass those to the generator. This pattern is standard in LlamaIndex and LangChain production setups. ---