Merge pull request #28161 from overleaf/bg-improved-index-for-lastBackedUpVersion

add improved index for null search on lastBackedUpVersion

GitOrigin-RevId: b938c3607b571053fe69d4a9330e8592c9f4ad02

services/web/migrations/20250827155732_optimise_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, _id: 1 },
+    name: 'overleaf.backup.id_1_lastBackedUpVersion_id_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,
+}