[solidangle]

> The ANN index IVF implemented in pgvector has very poor performance, with only around 50% recall.

My understanding is that this mostly due to the default settings that pgvector uses (nprobes = 3) and not due to the usage of IVF. The recall would improve significantly with better defaults. This of course would also increase the latency of vector searches, but that is the trade-off of using IVF instead of HNSW (worse latency at high recall, but much lower storage/memory costs).