⚡ Bolt: Optimize Playlist Thumbnail Query

.jules/bolt.md

@@ -0,0 +1,5 @@
+# Bolt's Journal
+
+## 2024-05-23 - Composite Index for Playlist Thumbnails
+**Learning:** SQLite query optimizer needs explicit composite indexes for `WHERE x = ? ORDER BY y` clauses to avoid in-memory sorting, especially when used in correlated subqueries.
+**Action:** Always check `ORDER BY` clauses in frequently run queries (like startup routines) and ensure covering indexes exist.

src/main/database.js

@@ -100,13 +100,19 @@ function initialize(app, customPath = null) {
           table.integer('sortOrder');
           table.primary(['playlistId', 'videoId']);
           table.index('playlistId');
+          table.index(['playlistId', 'sortOrder'], 'idx_playlist_video_sort');
         });
       } else {
         try {
           await db.schema.alterTable('playlist_videos', (t) =>
             t.index('playlistId')
           );
         } catch (e) {}
+        try {
+          await db.schema.alterTable('playlist_videos', (t) =>
+            t.index(['playlistId', 'sortOrder'], 'idx_playlist_video_sort')
+          );
+        } catch (e) {}
       }
 
       if (!(await db.schema.hasTable('artists'))) {

test/integration/database_advanced.test.js

@@ -123,4 +123,11 @@ describe('Advanced Database Logic', () => {
     expect(all.length).toBe(1);
     expect(all[0].name).toBe('Busy Artist');
   });
+
+  test('should have composite index on playlist_videos', async () => {
+    const db = database.getDB();
+    const indexes = await db.raw("PRAGMA index_list('playlist_videos')");
+    const hasIndex = indexes.some(idx => idx.name === 'idx_playlist_video_sort');
+    expect(hasIndex).toBe(true);
+  });
 });