Graph-based Associations Preloader for Rails' ActiveRecord

A faster way to preload complex ActiveRecord associations graphs that uses way less queries.

Why? Just check the logs. (TODO: Pics later)

How it works?

• Associations are added to the DAG (direct acyclic graph) where vetrices are "models" and edges are relationships between them.
• tsort the DAG in order to determine proper associations load order
• Load assocs using as few queries as possible. Best case scenario: one query per table (not per association as Rails does), though in presence of scopes there can be more queries per table.

TODO: proper description later

Supported Rails versions: 5.0 (later), 5.1 (only this one for now), 5.2 (later)

Installation

Add this line to your application's Gemfile:

# it's still alpha, I'll push it to Rubygems as soon as specs and perftests are done
gem 'fast_preloader', git: 'https://github.com/konukhov/fast_preloader'

And then execute:

$ bundle

Caveats

This gem is in early development so:

• Doest't support polymorphic records yet
• It cannot load circular references (User->Comment, Comment->User) yet. Rails can because it loads each association independently.
• I'm sure it has a lot of bugs

TODO: perf, specs etc.

Usage

Enable/disable globally:

# put it in config/initializers/fast_preloader.rb
FastPreloader.enable!

... for a particular model

class SomeModel < ApplicationRecord
  # enabled
  fast_preloader
  
  # same
  fast_preloader true 
  
  # disabled for this model if enabled globally
  fast_preloader false 
end

... or for a particuar query or scope

# enable for query
SomeModel.use_fast_preloader.includes(:some, associations: [:custom, :preloading])

# disable for query if enabled globally or for this model
SomeModel.use_fast_preloader(false).includes(:some, associations: [:rails, :preloading]) 

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/konukhov/fast_preloader. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Fast Preloader project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.