minstrel/internal/db/queries/discover.sql

-- Discover playlist bucket queries. Each returns up to its LIMIT
-- count of (track_id, album_id, artist_id) triples ordered
-- daily-deterministically via md5(track_id || dateStr). The Go-side
-- bucket allocator (internal/playlists/discover.go) applies
-- per-album (<=2) and per-artist (<=3) caps then redistributes any
-- bucket deficit equally across the others. LIMIT values are
-- generous so the caps + redistribution have headroom.

-- name: ListDormantArtistTracksForDiscover :many
-- Tracks whose artist this user has played fewer than 10 times total.
-- The artist threshold defines "dormant" — we want to surface the
-- long tail of artists in the user's library that they rarely listen
-- to. Excludes tracks the user has played, liked, or has quarantined.
-- $1 = user_id, $2 = date string for md5 ordering.
WITH user_artist_counts AS (
    SELECT t.artist_id, COUNT(*) AS play_count
      FROM play_events pe
      JOIN tracks t ON t.id = pe.track_id
     WHERE pe.user_id = $1
       AND pe.was_skipped = false
     GROUP BY t.artist_id
),
dormant_artists AS (
    SELECT a.id
      FROM artists a
      LEFT JOIN user_artist_counts uac ON uac.artist_id = a.id
     WHERE COALESCE(uac.play_count, 0) < 10
)
SELECT t.id, t.album_id, t.artist_id
  FROM tracks t
  JOIN dormant_artists da ON da.id = t.artist_id
 WHERE NOT EXISTS (
       SELECT 1 FROM play_events pe
        WHERE pe.user_id = $1
          AND pe.track_id = t.id
          AND pe.was_skipped = false
   )
   AND NOT EXISTS (
       SELECT 1 FROM general_likes gl
        WHERE gl.user_id = $1 AND gl.track_id = t.id
   )
   AND NOT EXISTS (
       SELECT 1 FROM lidarr_quarantine q
        WHERE q.user_id = $1 AND q.track_id = t.id
   )
 ORDER BY md5(t.id::text || $2::text)
 LIMIT 80;

-- name: ListCrossUserLikedTracksForDiscover :many
-- Tracks any OTHER user has liked, that this user hasn't played,
-- liked, or had quarantined. On single-user servers this returns 0
-- rows (the caller's slot redistribution rolls the deficit into the
-- other two buckets).
-- $1 = user_id, $2 = date string for md5 ordering.
--
-- GROUP BY (not SELECT DISTINCT) so the md5 ORDER BY expression need
-- not appear in the select list — Postgres rejects DISTINCT + ORDER BY
-- by-expression at plan time (SQLSTATE 42P10), which previously caused
-- the entire Discover build to fail silently.
SELECT t.id, t.album_id, t.artist_id
  FROM general_likes gl
  JOIN tracks t ON t.id = gl.track_id
 WHERE gl.user_id != $1
   AND NOT EXISTS (
       SELECT 1 FROM play_events pe
        WHERE pe.user_id = $1
          AND pe.track_id = t.id
          AND pe.was_skipped = false
   )
   AND NOT EXISTS (
       SELECT 1 FROM general_likes ml
        WHERE ml.user_id = $1 AND ml.track_id = t.id
   )
   AND NOT EXISTS (
       SELECT 1 FROM lidarr_quarantine q
        WHERE q.user_id = $1 AND q.track_id = t.id
   )
 GROUP BY t.id, t.album_id, t.artist_id
 ORDER BY md5(t.id::text || $2::text)
 LIMIT 60;

-- name: ListRandomUnheardTracksForDiscover :many
-- Random sample from the entire library. Same exclusion filters as
-- the other two buckets. The generous LIMIT (200) gives the caller
-- headroom for the per-album/artist caps and the slot redistribution.
-- $1 = user_id, $2 = date string for md5 ordering.
SELECT t.id, t.album_id, t.artist_id
  FROM tracks t
 WHERE NOT EXISTS (
       SELECT 1 FROM play_events pe
        WHERE pe.user_id = $1
          AND pe.track_id = t.id
          AND pe.was_skipped = false
   )
   AND NOT EXISTS (
       SELECT 1 FROM general_likes gl
        WHERE gl.user_id = $1 AND gl.track_id = t.id
   )
   AND NOT EXISTS (
       SELECT 1 FROM lidarr_quarantine q
        WHERE q.user_id = $1 AND q.track_id = t.id
   )
 ORDER BY md5(t.id::text || $2::text)
 LIMIT 200;

-- name: ListTasteUnheardTracksForDiscover :many
-- Taste-targeted novelty: unheard tracks whose genres overlap the user's
-- taste-profile tags (taste_profile_tags, #796), ranked by summed tag
-- weight — "new to you, but your vibe" rather than the crude random arm.
-- Genres live inline on tracks.genre as a delimited string, split the
-- same way the radio tag_overlap arm does (regexp_split_to_table on
-- [;,]). Same exclusion filters as the other buckets. Returns nothing
-- when the user has no taste tags yet (cold start), so the caller
-- redistributes its slots to the other buckets. Stamped 'taste_unheard'.
-- $1 = user_id, $2 = date string for md5 tiebreak ordering.
SELECT t.id, t.album_id, t.artist_id
  FROM tracks t
  JOIN LATERAL regexp_split_to_table(coalesce(t.genre, ''), '[;,]') AS g_split(g) ON true
  JOIN taste_profile_tags nt ON nt.user_id = $1 AND trim(g_split.g) = nt.tag
 WHERE nt.weight > 0
   AND trim(g_split.g) <> ''
   AND NOT EXISTS (
       SELECT 1 FROM play_events pe
        WHERE pe.user_id = $1
          AND pe.track_id = t.id
          AND pe.was_skipped = false
   )
   AND NOT EXISTS (
       SELECT 1 FROM general_likes gl
        WHERE gl.user_id = $1 AND gl.track_id = t.id
   )
   AND NOT EXISTS (
       SELECT 1 FROM lidarr_quarantine q
        WHERE q.user_id = $1 AND q.track_id = t.id
   )
 GROUP BY t.id, t.album_id, t.artist_id
 ORDER BY SUM(nt.weight) DESC, md5(t.id::text || $2::text)
 LIMIT 120;