There are Rails applications that run incredibly fast on a developer’s laptop, but the moment they are deployed to production, they crawl to a halt. The pages take 3 seconds to load, and the database CPU is at 100%.

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

N+1 queries are a common Rails performance killer where fetching associated records in a loop triggers hundreds of redundant database calls. The fix is eager loading via ActiveRecord's `.includes` method, which pre-fetches all related data in one or two queries instead of one per record. For nested associations, pass a hash to `.includes`. Under the hood, Rails has three eager loading strategies: `.preload` (two separate queries), `.eager_load` (a single LEFT OUTER JOIN, required when filtering on the joined table), and `.includes` (smart default that picks between the two). To catch N+1 bugs before they reach production, enable `strict_loading_by_default` in development, which raises an error the moment a lazy-loaded association is accessed.

How to Fix N+1 Queries in Rails Like a Pro

LEVEL 3: includes vs preload vs eager_load (The Pro Stuff)

LEVEL 4: Strict Loading (The Ultimate Safety Net)