Merge pull request #24186 from overleaf/bg-backup-index-on-missing-lastBackedUpVersion

add a mongo index to find projects which are not backed up

GitOrigin-RevId: d776ebac2bef348117dc87556156e4682ac1b3e3

services/web/migrations/20250307120446_create_project_lastBackedUpVersion_index.mjs

@@ -0,0 +1,31 @@
+/* eslint-disable no-unused-vars */
+
+import Helpers from './lib/helpers.mjs'
+
+const tags = ['saas']
+
+const indexes = [
+  {
+    key: { 'overleaf.backup.lastBackedUpVersion': 1 },
+    name: 'overleaf.backup.lastBackedUpVersion_1',
+    partialFilterExpression: {
+      'overleaf.backup.lastBackedUpVersion': { $in: [null] },
+    },
+  },
+]
+
+const migrate = async client => {
+  const { db } = client
+  await Helpers.addIndexesToCollection(db.projects, indexes)
+}
+
+const rollback = async client => {
+  const { db } = client
+  await Helpers.dropIndexesFromCollection(db.projects, indexes)
+}
+
+export default {
+  tags,
+  migrate,
+  rollback,
+}