Fix messages_preview index

ts/sql/migrations/49-fix-preview-index.ts

@@ -0,0 +1,33 @@
+// 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 updateToSchemaVersion49(
+  currentVersion: number,
+  db: Database,
+  logger: LoggerType
+): void {
+  if (currentVersion >= 49) {
+    return;
+  }
+
+  db.transaction(() => {
+    db.exec(
+      `
+      DROP INDEX messages_preview;
+
+      -- Note the omitted 'expiresAt' column in the index. If it is present
+      -- sqlite can't ORDER BY received_at, sent_at using this index.
+      CREATE INDEX messages_preview ON messages
+        (conversationId, shouldAffectPreview, isGroupLeaveEventFromOther, received_at, sent_at);
+      `
+    );
+
+    db.pragma('user_version = 49');
+  })();
+
+  logger.info('updateToSchemaVersion49: success!');
+}

ts/sql/migrations/index.ts

@@ -24,6 +24,7 @@ import updateToSchemaVersion45 from './45-stories';
 import updateToSchemaVersion46 from './46-optimize-stories';
 import updateToSchemaVersion47 from './47-further-optimize';
 import updateToSchemaVersion48 from './48-fix-user-initiated-index';
+import updateToSchemaVersion49 from './49-fix-preview-index';
 
 function updateToSchemaVersion1(
   currentVersion: number,
@@ -1911,6 +1912,7 @@ export const SCHEMA_VERSIONS = [
   updateToSchemaVersion46,
   updateToSchemaVersion47,
   updateToSchemaVersion48,
+  updateToSchemaVersion49,
 ];
 
 export function updateSchema(db: Database, logger: LoggerType): void {