Deluan ad566d0cb6 perf(db): add covering index for title-sorted song listings
Deep pagination over songs sorted by title (WHERE missing/library_id,
ORDER BY order_title LIMIT/OFFSET - the shape Jellyfin clients use to
enumerate the library, and non-admin native/Subsonic song lists share)
walked media_file_order_title and fetched the table row for every
skipped entry just to evaluate the filter and the annotation/bookmark
join keys: offset+limit random reads, seconds per page on cold spinning
disks.

The new (missing, library_id, order_title, id) index makes the offset
skip fully index-resident: filter columns and the join key come from the
index, and only the emitted page touches table rows. Measured on a
96K-track library: offset 50000 drops from ~6.5s (poisoned stats) /
~100ms (good stats, warm) to 24ms, and cold deep pages on NAS hardware
from ~7s to ~0.5s.
2026-07-08 23:29:41 -04:00
..