To complete the feature that I'm developing, I have to insert a large list of items into the database, it's simple but I would like to insert it in the shortest possible time. To do this I have enumerated two ways and I will compare the time for operations to decide which is the best.

To measure the time I'm using the very useful native ruby tool: Benchmark 

To prepare the environment I'm just using this recipe:

rails g model person name:string
rails db:migrate

* You can check out some tips for trying new things in Rails in the post - https://www.mateusnava.com/posts/a-simple-technique-for-trying-out-new-things-in-rails

The first option is the "classic", I open a transaction with the database and inside it, I insert records, one by one.

Person.transaction do
  5_000.times do
    Person.create!(name: Faker::Name.name)
  end
end

The result:

{
  "real": 5.51667699997779                                 
}  

For the second experiment, I'm using Active Record's insert_all method.

items = 5_000.times.map do
  {
    name: Faker::Name.name
  }
end

Person.insert_all(items)

The result:

{      
  "real": 1.5328290000325069
}  

🙀😱 This is much faster than the first option. 💜  insert_all

There are two important aspects to speeding up this operation:
- PostgreSQL multiline insert feature - single SQL INSERT statement (https://www.postgresql.org/docs/current/dml-insert.html)
- Rails does not instantiate any model (no trigger Active Record callbacks or validations)

Thanks :).