`record_updates` — the write behind the quality, eye and crop passes —
re-marked the image as indexed under the pipeline the pass ran as, and
left the faces it had updated under the id of the detector that found
them. On a desktop set to Thorough that put `scrfd_10g+w600k_mbf` over
faces spelled `w600k_mbf`; on the tablet, `scrfd_10g_i8+w600k_mbf` over
faces it had adopted from the desktop's thorough pass.
Every reader takes the marker and the faces to agree. `marker_under`
reads the marker as the detector having examined the image, so the
upgrade repair never revisits it. The shard store keys each face by
its pipeline id, so `export_to_shards` selects an image's faces by the
marker's id, finds none, and sends an entry that says the thorough
detector looked and found nothing — over photographs with named faces
on them. The desktop's shard index holds 54 such entries beside real
faces; the tablet's eye pass over the faces it had adopted made 430
more, and both devices have exchanged them. `held_model` takes the
newest entry for an image, which is the empty one. Nothing has been
lost yet only because the two spellings of the thorough detector rank
equal and neither side adopts the other's; a third device, or either
one after a reinstall, would adopt "nothing here" for 484 images. And
the desktop's eye pass is 4,739 images from doing the same to every
face from before V14 — which are the ones that only exist on the
desktop, and would then never reach anywhere.
The marker now takes the id the faces carry; the pass's own id is used
only when it dropped the last of them and there is no detector left to
name. A stale marker under another spelling of the same embedder is
removed in the same transaction, so one embedder has one marker.
dtourolle
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