Optimization Showdown: IN vs EXISTS for Large Subquery

Choose better query for large order table and selective customer region filter. Query A: SELECT * FROM orders WHERE customer_id IN (SELECT customer_id FROM customers WHERE region='APAC'); Query B: SELECT o.* FROM orders o WHERE EXISTS (SELECT 1 FROM customers c WHERE c.customer_id = o.customer_id AND c.region='APAC');

orders(order_id, customer_id, total_amount), customers(customer_id, region)