join_cache

Faster ActiveRecord associations using Rails cache.

What?

Let's say you scaffolded your Rails app and ended up with this:

class Employee < ActiveRecord::Base
  has_and_belongs_to_many :teams
end

Retrieving the teams of one employee generates an inner join:

bob.teams
=> Team Load SELECT "teams".* FROM "teams" INNER JOIN "employees_teams" ON "teams"."id" = "employees_teams"."team_id" WHERE "employees_teams"."employee_id" = ?  [["employee_id", 1]]

The gem join_cache generates methods to store the team ids in cache:

bob.cached_team_ids
=> [4, 8, 15, 16, 23, 42]

bob.cached_teams
=> Team.where(id: [4, 8, 15, 16, 23, 42])
=> Team Load SELECT "teams".* FROM "teams" WHERE "teams"."id" IN (4, 8, 15, 16, 23, 42)

Usage

In your gemfile:

gem 'join_cache'

In your model:

class Employee < ActiveRecord::Base
  has_and_belongs_to_many :teams
  include JoinCache # make sure to add this *after* listing the associations
end

It also works with has_many :through associations!

class Physician < ActiveRecord::Base
  has_many :appointments
  has_many :patients, through: :appointments
  include JoinCache
end

freud.patients
=> Patient Load SELECT "patients".* FROM "patients" INNER JOIN "appointments" ON "patients"."id" = "appointments"."patient_id" WHERE "appointments"."physician_id" = ?  [["physician_id", 1]]

freud.cached_patient_ids
=> [4, 8, 15, 16, 23, 42]

freud.cached_patients
=> Patient.where(id: [4, 8, 15, 16, 23, 42])
=> Patient Load SELECT "patients".* FROM "patients" WHERE "patients"."id" IN (4, 8, 15, 16, 23, 42)

Take a look at this example app.

Performance

I ran a very scientific study using Heroku, PostgreSQL, the example app, its seeds.rb and speed.rake files. Shorter means better:

See? 30% faster!

TODO

• Support callbacks: after_add and after_remove
• Support cached_ids for all collection associations

View the full list

Contributing to join_cache

• Fork the project.
• Start a feature/bugfix branch.
• Commit and push until you are happy with your contribution.

I came here looking for Johnny Cash

Here you go:

Copyright

Copyright (c) 2013 Kevin Bongart. See LICENSE.txt for further details.