Pagy VS rack-mini-profiler

Now, let's dive into the pagination part of this post: setting up Pagy for handling pagination in our Rails application. If you haven't included the Pagy gem in your project, you'll need to add it manually. Here's how you can do it:

Several gems are available for pagination in Rails, but the Pagy gem is one of the most popular and efficient. It is a fast and lightweight library that provides a simple and flexible API. In this article, we’ll explore how to use it to implement pagination in Rails.

> Am I understanding correctly that there’s a significant difference in performance between using a ViewComponent + a partial vs. a ViewComponent which renders html via a tag - from inside the component?

I don't think there will be much difference at all in everyday use, but some libraries that value performance don't avoid templates for that reason, Pagy for example.

https://github.com/ddnexus/pagy

Personally I omit them in my projects whenever we want to customise attributes, I hate seeing stuff like this in templates:

    
Some header

The next step was about backporting the templates, adding Pagy gem for handling pagination and creating the controller. I was then able to show the listings with the models, but the filtering was not working.

On the backend, we'll need a few tools. Apart from the classics (ActiveRecord scopes and the pg_search gem), you’ll see how the (yet officially unreleased but production-tested) all_futures gem, built by SR authors, will act as an ideal ephemeral object to temporarily store our filter params and host our search logic. Finally, we’ll use pagy for pagination duties.

Pagination

In our application, we will use Pagy to implement pagination. Let’s install Pagy now, following along with the Pagy quick start guide.

For pagination I tend not to use gems like pagy or kaminari, instead implement this functionality just using limit and offset.

Kaminari hooks onto ActiveRecord associations and makes it super easy to page them. Pagy is another option that seems to have a solid API but I haven't tried it yet.

But how is this implemented? Well, if you use pagination in your index methods with gems like pagy, kaminari or will_paginate you will find that the same idea is happening here, they are using the power of SQL's LIMIT and OFFSET to fetch only a portion of the data each time. So in the 1 million users example, find_each will perform 1000 thousand queries with a limit of 1000 while changing the offset properly so we don't miss any record.

Author of peek here. Honestly, I got burnt out. We stopped using this internally at GitHub which made it difficult to continue working on. Rails was going through its identity crisis with asset pipelines.

https://github.com/MiniProfiler/rack-mini-profiler gets you most of the way there and comes by default in the Gemfile for new Rails applications.

This already exists to some degree: https://github.com/MiniProfiler/rack-mini-profiler

rack-mini-profiler will generate flamegraphs for Rails backend requests.

Have you tried using https://github.com/MiniProfiler/rack-mini-profiler to get a clear breakdown of where your server is spending it's time filling the requests? If rack-mini-profiler is too much for you to deal with right now, you can still get a good idea just using the https://github.com/ruby/benchmark gem and wrapping some of your requests in a benchmark.

# Bundle edge Rails instead: gem "rails", github: "rails/rails", branch: "main" gem "rails", "~> 7.0.4" # The original asset pipeline for Rails [https://github.com/rails/sprockets-rails] gem "sprockets-rails" # Use sqlite3 as the database for Active Record gem "sqlite3", "~> 1.4" # Use the Puma web server [https://github.com/puma/puma] gem "puma", "~> 5.0" # Use JavaScript with ESM import maps [https://github.com/rails/importmap-rails] gem "importmap-rails" # Hotwire's SPA-like page accelerator [https://turbo.hotwired.dev] gem "turbo-rails" # Hotwire's modest JavaScript framework [https://stimulus.hotwired.dev] gem "stimulus-rails" # Build JSON APIs with ease [https://github.com/rails/jbuilder] gem "jbuilder" # Windows does not include zoneinfo files, so bundle the tzinfo-data gem gem "tzinfo-data", platforms: %i[ mingw mswin x64_mingw jruby ] # Reduces boot times through caching; required in config/boot.rb gem "bootsnap", require: false # Use Sass to process CSS # gem "sassc-rails" # Use Active Storage variants [https://guides.rubyonrails.org/active_storage_overview.html#transforming-images] # gem "image_processing", "~> 1.2" group :development, :test do # See https://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-the-debug-gem gem "debug", platforms: %i[ mri mingw x64_mingw ] end group :development do # Use console on exceptions pages [https://github.com/rails/web-console] gem "web-console" # Add speed badges [https://github.com/MiniProfiler/rack-mini-profiler] # gem "rack-mini-profiler" # Speed up commands on slow machines / big apps [https://github.com/rails/spring] # gem "spring" end group :test do # Use system testing [https://guides.rubyonrails.org/testing.html#system-testing] gem "capybara" gem "selenium-webdriver" gem "webdrivers" end

rack-mini-profiler

For a quick ad hoc peek at the performance of pages that you can request yourself, without having to go through the hoops of connecting to and committing to an external service, this gem can also be useful: https://github.com/MiniProfiler/rack-mini-profiler