Improve performance of migration 211 (adding mostImportantRole to sessions) (#19700)

app/models/server/models/Sessions.js

@@ -434,6 +434,7 @@ export class Sessions extends Base {
 		this.tryEnsureIndex({ instanceId: 1, sessionId: 1, userId: 1 });
 		this.tryEnsureIndex({ instanceId: 1, sessionId: 1 });
 		this.tryEnsureIndex({ sessionId: 1 });
+		this.tryEnsureIndex({ userId: 1 });
 		this.tryEnsureIndex({ year: 1, month: 1, day: 1, type: 1 });
 		this.tryEnsureIndex({ type: 1 });
 		this.tryEnsureIndex({ ip: 1, loginAt: 1 });

server/startup/migrations/v211.js

@@ -28,8 +28,21 @@ async function migrateSessions() {
 		$match: { 'user.roles.0': { $exists: 1 } },
 	}]);
 
+	let actions = [];
 	for await (const session of cursor) {
-		await Sessions.col.updateMany({ userId: session._id }, { $set: { mostImportantRole: getMostImportantRole(session.user.roles) } });
+		actions.push({
+			updateMany: {
+				filter: { userId: session._id },
+				update: { $set: { mostImportantRole: getMostImportantRole(session.user.roles) } },
+			},
+		});
+		if (actions.length === 100) {
+			await Sessions.col.bulkWrite(actions, { ordered: false });
+			actions = [];
+		}
+	}
+	if (actions.length) {
+		await Sessions.col.bulkWrite(actions, { ordered: false });
 	}
 }