Improve performance of scrobble activity queries

.claude/settings.local.json

@@ -40,7 +40,8 @@
       "Bash(MIX_ENV=test mix ecto.migrate:*)",
       "WebFetch(domain:api-dashboard.search.brave.com)",
       "WebFetch(domain:api.search.brave.com)",
-      "Bash(while read dir)"
+      "Bash(while read dir)",
+      "Bash(MIX_ENV=dev mix run:*)"
     ]
   },
   "enableAllProjectMcpServers": false

priv/repo/migrations/20260216115654_add_scrobbled_tracks_indexes.exs

@@ -0,0 +1,47 @@
+defmodule MusicLibrary.Repo.Migrations.AddScrobbledTracksIndexes do
+  use Ecto.Migration
+
+  def change do
+    # Helps GROUP BY in get_top_albums / get_top_albums_by_days
+    # Also helps the WHERE json_extract(album, '$.title') != '' filter
+    execute(
+      """
+      CREATE INDEX scrobbled_tracks_album_title_artist_name_index
+        ON scrobbled_tracks(
+          json_extract(album, '$.title'),
+          json_extract(artist, '$.name')
+        )
+      """,
+      "DROP INDEX scrobbled_tracks_album_title_artist_name_index"
+    )
+
+    # Helps GROUP BY in get_top_artists / get_top_artists_by_days
+    execute(
+      """
+      CREATE INDEX scrobbled_tracks_artist_name_index
+        ON scrobbled_tracks(json_extract(artist, '$.name'))
+      """,
+      "DROP INDEX scrobbled_tracks_artist_name_index"
+    )
+
+    # Helps LEFT JOIN to collection/wishlist subqueries
+    # (join condition: cr.release_id == json_extract(t.album, '$.musicbrainz_id'))
+    execute(
+      """
+      CREATE INDEX scrobbled_tracks_album_musicbrainz_id_index
+        ON scrobbled_tracks(json_extract(album, '$.musicbrainz_id'))
+      """,
+      "DROP INDEX scrobbled_tracks_album_musicbrainz_id_index"
+    )
+
+    # Helps LEFT JOIN to artist_infos
+    # (join condition: ai.id == json_extract(t.artist, '$.musicbrainz_id'))
+    execute(
+      """
+      CREATE INDEX scrobbled_tracks_artist_musicbrainz_id_index
+        ON scrobbled_tracks(json_extract(artist, '$.musicbrainz_id'))
+      """,
+      "DROP INDEX scrobbled_tracks_artist_musicbrainz_id_index"
+    )
+  end
+end