From 6d9110e064dbac39ae7543b20a8e5eadf40f59b2 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Fri, 23 Jan 2026 13:07:34 +0000
Subject: [PATCH] perf: add composite index for playlist thumbnails
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- Add `idx_playlist_video_sort` composite index on `(playlistId, sortOrder)` to `playlist_videos` table.
- Optimizes `getAllPlaylistsWithStats` query by avoiding in-memory sort for thumbnail selection.
- Add verification test in `test/integration/database_advanced.test.js`.
- Add performance journal entry.

⚡ Bolt Optimization: ONE small performance improvement.
---
 .jules/bolt.md                             | 5 +++++
 src/main/database.js                       | 6 ++++++
 test/integration/database_advanced.test.js | 7 +++++++
 3 files changed, 18 insertions(+)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..72edf64
--- /dev/null
+++ b/.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.
diff --git a/src/main/database.js b/src/main/database.js
index 03efb71..0d942b1 100644
--- a/src/main/database.js
+++ b/src/main/database.js
@@ -100,6 +100,7 @@ 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 {
@@ -107,6 +108,11 @@ function initialize(app, customPath = null) {
             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'))) {
diff --git a/test/integration/database_advanced.test.js b/test/integration/database_advanced.test.js
index 320c895..630ccb8 100644
--- a/test/integration/database_advanced.test.js
+++ b/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);
+  });
 });