Optimize loading stories

ts/sql/migrations/70-story-reply-index.ts

@@ -0,0 +1,29 @@
+// Copyright 2021-2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { Database } from 'better-sqlite3';
+
+import type { LoggerType } from '../../types/Logging';
+
+export default function updateToSchemaVersion70(
+  currentVersion: number,
+  db: Database,
+  logger: LoggerType
+): void {
+  if (currentVersion >= 70) {
+    return;
+  }
+
+  db.transaction(() => {
+    // Used in `getAllStories`.
+    db.exec(
+      `
+      CREATE INDEX messages_by_storyId ON messages (storyId);
+      `
+    );
+
+    db.pragma('user_version = 70');
+  })();
+
+  logger.info('updateToSchemaVersion70: success!');
+}