Count the label chips from the labelled versions, not from every image

`label_histogram` runs on every label keystroke and after every batch of
judgements is saved. On the reference library it cost 7.2-8.4 ms best-of-50
by catalog_bench (13 ms on a busy machine), to report that none of 23,500
images carried a label.

The join was the rating histogram's, with one thing worse: the index does
not carry `label`, so each probe went on to read the version's row.

  SCAN i USING COVERING INDEX images_folder
  SEARCH v USING INDEX versions_judgement (image_id=?) LEFT-JOIN
  USE TEMP B-TREE FOR GROUP BY

It now takes the rating histogram's shape: only labelled default versions
are grouped, and the unlabelled slot is what is left of `judged_rows`.

  SCAN versions USING INDEX versions_judgement
  USE TEMP B-TREE FOR GROUP BY          (the labelled rows only)

That pass still reads each default version's row for `label`, but in the
index's order, which follows the table's; a partial index on the labelled
rows would make it index-only, and was not worth a new index for the
remaining 1 ms. After: 1.7-2.0 ms, the same answer on the reference library,
and a test that compares it with the old join over the awkward states the
rating test uses (a second default's label counted, unknown codes and zero
folded into unlabelled).
This commit is contained in:
2026-09-26 13:28:50 -04:00
parent 81118728f4
commit 73059f2656
2 changed files with 37 additions and 13 deletions
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