Scrolling jittered, and this was the largest single reason. Every window the
grid loads is `ORDER BY ... LIMIT n OFFSET k`, and neither half of that was
being answered the cheap way.
**The sort.** `GRID_ORDER` leads with `captured_at IS NULL`, so undated frames
fall to the end. No ordinary index answers that — the leading term is an
expression, not a column — so SQLite sorted the whole library into a temp
b-tree on every window read, then threw away the first `k` rows of it. Schema
V7 indexes the expression exactly as the query writes it, partial on the same
`shadowed_by IS NULL AND trashed_at IS NULL` the grid filters by, so the read
becomes a walk along the index.
**The join.** `LEFT JOIN remote` was paged *after* it was joined, so reading
280 cells at offset 20,000 first seeked into `remote` for all 24,000 rows and
then discarded 23,720 of them. The file ids are now fetched for the 280 rows
that survived — the shape the badge and rating reads already use, one query for
the window rather than one per cell.
Measured together on 24,000 images at offset 20,000: **15.2 ms → 0.36 ms**,
inside a scroll handler that has 16.7 ms to draw a frame.
The test asserts on the query plan rather than on a duration, because there is
no other symptom. A `GRID_ORDER` edited out of step with the index, or a column
added back that drags `remote` in again, both still return exactly the right
cells — just after sorting the library — and the jitter would come back with
nothing to point at.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
dtourolleandClaude Opus 5
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