til/rails/create-table-with-bigint-id-as-primary-key.md

Create Table With bigint ID As Primary Key

When creating a new table with an ActiveRecord migration, we specify all the fields except the id. The id, which is the primary key, is implicit. We get it by default.

The type of that id defaults to int which is a 32-bit signed integer.

We can override the type of id in a variety of ways. The one I prefer in most cases is to make the id of type bigint. This is a 64-bit signed integer. It offers quite a bit more headroom for the number of unique identifies in our table.

This can be specified by including id: :bigint as an option to the create_table method.

class CreatePosts < ActiveRecord::Migration[8.0]
  def change
    create_table :posts, id: :bigint do |t|
      t.string :title, null: false
      t.string :body, null: false

      t.timestamps
    end
  end
end

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