This SQL query takes 45 seconds on a table with 10M rows. Rewrite it to run in under 1 second. Explain your optimization strategy. ```sql SELECT u.name, u.email, (SELECT COUNT(*) FROM orders o WHERE o.user_id = u.id) as order_count, (SELECT SUM(amount) FROM orders o WHERE o.user_id = u.id) as total_spent, (SELECT MAX(created_at) FROM orders o WHERE o.user_id = u.id) as last_order FROM users u WHERE u.created_at > '2024-01-01' AND (SELECT COUNT(*) FROM orders o WHERE o.user_id = u.id) > 5 ORDER BY total_spent DESC LIMIT 100; ``` Assume standard B-tree indexes on primary keys only. What indexes would you add?