The latest articles on DEV Community by Kerochan (@kerochan). https://dev.to/kerochan https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3909036%2Fb27221fd-3727-49f1-9215-459e8cd5223b.jpeg https://dev.to/kerochan en Kerochan Sun, 03 May 2026 19:07:52 +0000 https://dev.to/kerochan/why-i-enforce-booking-concurrency-at-the-database-layer-and-not-in-nodejs-38im https://dev.to/kerochan/why-i-enforce-booking-concurrency-at-the-database-layer-and-not-in-nodejs-38im <p>Booking systems have an inherent problem: race conditioning.</p> <p>A naive approach of fixing it is checking availability before inserting a booking, but it <em>still</em> introduces a race condition where multiple requests can pass validation simultaneously.</p> <p>This is why we need a DB constraint solution, using a UNIQUE constraint on time_slot_id in the bookings table.</p> <p>Here is my project for proof: <a href="https://kerochan.lol/blog/pern.html" rel="noopener noreferrer">https://kerochan.lol/blog/pern.html</a><br> <a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fy60hcn9jml2sz1gt6lo5.jpg" class="article-body-image-wrapper"><img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fy60hcn9jml2sz1gt6lo5.jpg" alt=" " width="540" height="540"></a></p> postgres backend webdev node