Constraints

Enforce Non-Overlapping Time Ranges with PostgreSQL Exclusion Constraints

Applications that schedule rooms, equipment, or maintenance windows often need a simple invariant: two active reservations for the same resource must not overlap. Checking for conflicts in application code looks easy, but concurrent transactions can both pass the check before either inserts. PostgreSQL can enforce this invariant inside the database with range types and exclusion constraints. Model the interval explicitly A half-open timestamp range includes its start and excludes its end. That lets adjacent bookings touch without overlapping.