Every sync pass exports this device's faces to the shard store and imports
what peers sent, and both walked the whole library asking the store's index
about one image at a time: the export 19,000 `indexed_at` lookups (one per
face marker), the import 23,000 `held_model` lookups (one per image with a
server id), each a statement prepared and run against the index. With
nothing new either way -- the usual pass -- that was all they did.
Measured with catalog_bench against copies of the reference catalog and
face store, best of 5, CPU:
export_to_shards (steady) 119 ms -> 27 ms
import_from_shards (steady) 250 ms -> 87 ms
Each now reads the index in one statement into a map. The import's query
is `held_model`'s, ordered the same way, keeping the first row per file,
and nothing in the loop changes which pipeline a file is held under
(`set_indexed_at` touches only a file already decided; candidates are
distinct files). The export's `put_image_at` does rewrite entries -- but
only its own file's, its generation and the siblings it supersedes -- so a
file already written in this pass is asked of the store again, and every
other answer is the one the lookup would have given. An index that cannot
be read gives an empty map, which is what each failed lookup returned.
The store index and the catalog are identical after the old and new
builds' runs.
dtourolle
2fd1b0b8ce