February 13, 2026 Range on Rails: How PostgreSQL Multirange Turned Complex Booking Logic into Elegant Simplicity At Kaigi on Rails 2025, Tomohiro Umeda from RIZAP Technologies presented a real-world backend engineering case study: how to build a flexible reservation system — without fixed time slots — using PostgreSQL’s Range and Multirange types. The talk, titled:…

RubyFlow's platform is a resource for Ruby developers, offering insights into Ruby programming language, Ruby on Rails framework, and Ruby-related tools. Through articles, tutorials, and community discussions, RubyFlow offers insights into building web applications with Ruby and Rails. Developers can learn about Ruby gems, Rails conventions, and best practices in Ruby development to write clean and maintainable code.

Ruby Flow

PostgreSQL's multirange types (available since version 14) can dramatically simplify complex booking and availability logic by treating time constraints as mathematical set operations. A case study from RIZAP Technologies demonstrates how chocoZAP's flexible reservation system—which allows arbitrary time intervals instead of fixed slots—uses multirange to compute availability through set difference operations. The approach involves aggregating unavailable periods into multiranges, performing subtraction in SQL, and exposing results through Rails views, eliminating tangled conditional logic while improving performance and maintainability.

Range on Rails: How PostgreSQL Multirange Turned Complex Booking Logic into Elegant Simplicity

The Problem: Reservations Without Fixed Slots

The Key Insight: Model Everything as Time Ranges

The Breakthrough: Multirange (PostgreSQL 14+)

Perform all multirange logic in SQL using a VIEW