RandomOrder

With this gem, you can return a random record from the database using SQL or use random scope to return records in random order.

Usage

Works with MySQL, SQLite, PostgreSQL.

This gem is adding three methods to ActiveRecord Relations - random and fast_random(n = 1).

You can do the following:

u1 = User.create(name: 'Lilith')
u2 = User.create(name: 'Metamorph')
u3 = User.create(name: 'Diablo')

assert_equal User.random.is_a?(ActiveRecord::Relation), true
assert_equal User.fast_random.is_a?(ActiveRecord::Relation), true

Fast Random method

As you may know order by RANDOM() might be slow in case you have many records in DB. I think the case I suggest to use another method which is bundled with this gem fast_random which is using another SQL to return random records from DB. It has some limitations like your table must have a primary key column. Simple benchmark on the table with 113000 records shows that it's faster. See screenshot with logs below:

n = 1000

Benchmark.bm do |benchmark|
  benchmark.report("random.limit(10)") do
    n.times do |nn|
      Events.random.limit(10).to_a
    end
  end

  benchmark.report("fast_random(10)") do
    n.times do |nn|
      Events.fast_random(10).to_a
    end
  end
end
                    user     system      total        real
random.limit(10)  2.612499   0.193492   2.805991 (1162.501909)
fast_random(10)   2.234706   0.140195   2.374901 ( 37.173482)

# Find one random record
Benchmark.bm do |benchmark|
  benchmark.report("random.first.id") do
    n.times do |nn|
      Events.random.first.id
    end
  end

  benchmark.report("fast_random.first.id") do
    n.times do |nn|
      Events.fast_random.first.id
    end
  end
end
#
                        user     system      total        real
random.first.id       2.014658   0.134942   2.149600 (1151.981899)
fast_random.first.id  1.661777   0.067484   1.729261 ( 35.350424)
#

Examples:

User.friends.random # return ActiveRecord::Relation with user`s random friends
User.random.first.friends.random # return ActiveRecord::Relation with random user`s random friends
Post.published.random.limit(3) # return ActiveRecord::Relation with 3 published posts
Post.published.fast_random(3) # --//-- and faster

Installation

Add this line to your application's Gemfile:

gem 'random_order'

And then execute:

$ bundle

Or install it yourself as:

$ gem install random_order

TODO

• oracle adapter
• sqlserver adapter
• MongoDB with Mongoid

Contributing

Contribution directions go here.

Source

https://rubygems.org/gems/random_order

License

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