Zero downtime migration

migration.rb

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# Please Note: this version requires https://github.com/khiav223577/in_batches #
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class AddLifecycleWebPushPermittedToUsers < ActiveRecord::Migration
  disable_ddl_transaction!
  
  def up
    ActiveRecord::Base.transaction do
      add_column :users, :lifecycle_web_push_permitted, :boolean, default: nil
      execute('ALTER TABLE users ALTER COLUMN lifecycle_web_push_permitted SET DEFAULT false')
    end

    User.unscoped.in_batches.update_all(lifecycle_web_push_permitted: false)
  end
end