By Muhammad Ali Mughal · Last updated 24 October 2026

Two customers click "Book" on the last slot at the same moment. Both see a confirmation. One of them shows up to find the truck, room or appointment already taken. If you want to prevent double booking, checking availability in your code before inserting isn't enough. The database has to enforce the rule, using a constraint, a row lock or both, and short-lived holds need an expiry so abandoned checkouts don't block real customers.

I'm Muhammad Ali Mughal, and at Loop Origin we build booking and operations software, including a Car Carrier Management System for a vehicle transport business in Pakistan, built on Laravel and PostgreSQL.…