enhance(backend): DB note (userId) インデクス -> (userId, id) 複合インデクスにする (#15879)

* enhance(backend): use composite index for ordering notes by user

Signed-off-by: eternal-flame-AD <yume@yumechi.jp>

* fixup! enhance(backend): use composite index for ordering notes by user

---------

Signed-off-by: eternal-flame-AD <yume@yumechi.jp>

3 files changed, 23 insertions, 1 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0524d3c5bb..d36cb8dd2b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@
 - Enhance: ジョブキューの成功/失敗したジョブも一定数・一定期間保存するようにし、後から問題を調査することを容易に
 - Enhance: フォローしているユーザーならフォロワー限定投稿のノートでもアンテナで検知できるように  
 	(Cherry-picked from https://github.com/yojo-art/cherrypick/pull/568 and https://github.com/team-shahu/misskey/pull/38)
+- Enhance: ユーザーごとにノートの表示が高速化するように
 - Fix: システムアカウントの名前がサーバー名と同期されない問題を修正
 - Fix: 大文字を含むユーザの URL で紹介された場合に 404 エラーを返す問題 #15813
 - Fix: リードレプリカ設定時にレコードの追加・更新・削除を伴うクエリを発行した際はmasterノードで実行されるように調整( #10897 )
diff --git a/packages/backend/migration/1745378064470-composite-note-index.js b/packages/backend/migration/1745378064470-composite-note-index.js
new file mode 100644
index 0000000000..49e835d38c
--- /dev/null
+++ b/packages/backend/migration/1745378064470-composite-note-index.js
@@ -0,0 +1,21 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+export class CompositeNoteIndex1745378064470 {
+	name = 'CompositeNoteIndex1745378064470';
+
+	async up(queryRunner) {
+		await queryRunner.query(`CREATE INDEX "IDX_724b311e6f883751f261ebe378" ON "note" ("userId", "id" DESC)`);
+		await queryRunner.query(`DROP INDEX IF EXISTS "IDX_5b87d9d19127bd5d92026017a7"`);
+		// Flush all cached Linear Scan Plans and redo statistics for composite index
+		// this is important for Postgres to learn that even in highly complex queries, using this index first can reduce the result set significantly
+		await queryRunner.query(`ANALYZE "user", "note"`);
+	}
+
+	async down(queryRunner) {
+		await queryRunner.query(`DROP INDEX IF EXISTS "IDX_724b311e6f883751f261ebe378"`);
+		await queryRunner.query(`CREATE INDEX "IDX_5b87d9d19127bd5d92026017a7" ON "note" ("userId")`);
+	}
+}
diff --git a/packages/backend/src/models/Note.ts b/packages/backend/src/models/Note.ts
index 9a95c6faab..c5ca2b5776 100644
--- a/packages/backend/src/models/Note.ts
+++ b/packages/backend/src/models/Note.ts
@@ -10,6 +10,7 @@ import { MiUser } from './User.js';
 import { MiChannel } from './Channel.js';
 import type { MiDriveFile } from './DriveFile.js';
 
+@Index(['userId', 'id'])
 @Entity('note')
 export class MiNote {
 	@PrimaryColumn(id())
@@ -65,7 +66,6 @@ export class MiNote {
 	})
 	public cw: string | null;
 
-	@Index()
 	@Column({
 		...id(),
 		comment: 'The ID of author.',