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Retrieval & EmbeddingsHard· Quantization· Reranking· Memory Optimization

PQ made the index 30x smaller and recall@10 dropped six points. You add exact reranking to recover it. What just happened to your budget?

Reranking requires full-precision vectors to be available. Consequently, the 1.09 GB index acquires a 15.36 GB companion in float16, causing the real compression ratio to fall from 30.5x to 2.0x. You must decide whether to keep the refine set resident in RAM, push it to SSD and accept the latency, or widen the PQ ‘m’ parameter to reduce the number of candidates needing refinement.

Code playground (Python)