The drain queried `date_taken IS NULL OR date_taken_source = 'fs_time'`
ORDER BY id ASC LIMIT 500 every watcher tick. The resolver is
deterministic on file bytes + filename + fs metadata, so any row that
landed on fs_time once landed there again on every retry — the drain
spun on the same lowest-id rows in perpetuity, never advancing to
rows 501+ while still logging more_remain=true.
Side effect: 500 auto-commit UPDATEs per tick sustained the SQLite
write lock long enough that other writers on separate DAO connections
hit the 5s busy_timeout. Manifested as intermittent 500s on
PATCH /image/faces/{id} that succeeded on retry.
Narrow the partial index and query predicate to `date_taken IS NULL`.
If exiftool installs or a new filename regex lands, an operator can
re-resolve fs_time rows out-of-band rather than re-introducing the
steady-state churn.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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