ArcFace embeddings quantized to 16-bit pgvector HALFVEC ? [D]

512-dim face embeddings as 32-bit floats are 2048 bytes, plus a 4-8 byte header, putting them just a hair over over PostgreSQL's TOAST threshold (2040 bytes), meaning by default postgresql always dumps them into a TOAST table instead of keeping them in line (result: double the I/O because it has to look up a data pointer and do another read