How PostgreSQL Can Prevent Overlapping Reservations
Most booking apps detect overlapping reservations in application code: pull all stays for the property, loop through them, compare date ranges. This works until two HTTP requests fly in at the same time and the database commits both. Welcome to Saturday lunch with two families standing at the front door of the same vacation home.
The fix is to push the conflict check down into the database, using PostgreSQL's tstzrange type and an EXCLUDE constraint. The result is bulletproof: even under perfectly-concurrent transactions, the database itself rejects the second booking with a constraint violation.
I'll walk through the pattern below, with the schema and a small test. This is the conflict-detection core of Ripazo, the booking app I'm building for families who co-own a vacation home.
The naive approach (and why it breaks)
Here's how most of us reach for it on day one:
async function createBooking(propertyId: string, start:...
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