Two scheduler jobs full-seq-scanned the 257k-row videos table every run:
- PERF-17 enrich_pending (`WHERE enriched_at IS NULL LIMIT N`, every few minutes):
44,680 buffers even with 0 pending -> a partial ix_videos_enrich_pending makes
it a 1-buffer index scan (empty when nothing pending).
- PERF-18 maintenance revalidate (`WHERE unavailable_since IS NULL ORDER BY
last_checked_at NULLS FIRST LIMIT N`, ~300 pages/run): 44,754 buffers + top-N
sort -> a partial ix_videos_recheck_order in that exact order = a 42-buffer
index scan. The order_by is rewritten to `asc().nulls_first()` (equivalent to
the old `(IS NULL) DESC, ASC`) so it rides the index; the unused plain
ix_videos_last_checked_at is dropped.
PERF-3: drop the never-picked boolean btrees (is_short, via_explore) and slim the
useful ones to partials over the queried subset (via_search=true, NOT
shorts_probed, unavailable_since IS NOT NULL) — less write amplification on the
biggest table, same lookups. Model: those 6 columns lose their inline index=True
(the partials are migration-defined, like the search_vector GIN); live_status
left alone.
Measured on the prod-sized localdev reseed: enrich 44,680 -> 1 buffer (25.9 ->
0.02 ms), maintenance 44,754 -> 42 buffers (35.5 -> 0.17 ms); all 11 CONCURRENTLY
index ops on 257k rows in 0.75s. Gate green (346 pytest incl. drift + downgrade
round-trip).
peter
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