Item 1 of #3072. Both sweeps issued a single-row pg_insert(image_tag)
from inside their per-image loop. Steady state that is nothing; a first
sweep over a back-catalogue is one round-trip per applied tag, tens of
thousands of them. Each chunk now collects its rows and writes them in
one statement.
The ticket suggested one insert per chunk PER TAG. A single multi-row
VALUES carries every tag at once, so it is one statement per chunk full
stop — and the sweeps already accumulate across all heads before they
commit, so nothing had to be restructured to allow it.
Not a new helper: wip_title.apply_wip_image_tags was already doing the
chunked ON CONFLICT DO NOTHING insert, so that shape is extracted to
services/image_tag_apply.insert_image_tags and all three writers share
it. The extraction deliberately leaves wip_title's pre-SELECT behind
rather than pulling it into the shared function — the sweeps don't need
it (their `skip` sets already exclude applied and rejected images) and
it exists only to produce an accurate count, which the sweeps also
compute themselves. So the shared primitive returns nothing: psycopg
reports rowcount -1 for a multi-row ON CONFLICT DO NOTHING insert, and a
count taken from the statement would be a lie rather than an
approximation.
Ordering note for the system-tag sweep: tag rows are now written after
that chunk's PresentationReview rows rather than interleaved before
them. Safe — PresentationReview FKs to image_record and tag, not to
image_tag.
Chunk size stays 5000: 5000 rows x 3 bound params = 15000, inside
Postgres' 65535-parameter ceiling with room to spare.
tests/test_image_tag_apply.py covers the primitive directly, since it is
now the single place three writers can be wrong at once — most
importantly that a re-run never restamps a hand-applied tag's source,
which would silently poison head training (it excludes the auto
sources).
Left alone: _insert_presentation_review is still per-row, and the
retract path still deletes per-row. Both operate on sets that are small
by construction, unlike the apply path.
Refs #3072
bvandeusen
5a0e1bbd03