Fix messages_unread index

ts/sql/migrations/50-fix-messages-unread-index.ts

@@ -0,0 +1,32 @@
+// Copyright 2021 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 updateToSchemaVersion50(
+  currentVersion: number,
+  db: Database,
+  logger: LoggerType
+): void {
+  if (currentVersion >= 50) {
+    return;
+  }
+
+  db.transaction(() => {
+    db.exec(
+      `
+      DROP INDEX messages_unread;
+
+      -- Note: here we move to the modern isStory/storyId fields and add received_at/sent_at.
+      CREATE INDEX messages_unread ON messages
+        (conversationId, readStatus, isStory, storyId, received_at, sent_at) WHERE readStatus IS NOT NULL;
+      `
+    );
+
+    db.pragma('user_version = 50');
+  })();
+
+  logger.info('updateToSchemaVersion50: success!');
+}