zero_downtime_add_column_with_constraint_migration_2.rb

class PopulateUsersNewColumnDefaultValue < ActiveRecord::Migration
  disable_ddl_transaction!
  
  def up
    User.find_in_batches do |users|
      User.where(id: users.map(&:id), new_column: nil)
          .update_all(new_column: "default_value")
    end  
  end  
end