gistfile1.rb

class AddTimestampsToFoosAndBarsMigration < Sequel::Migration

  def up
    time_type = defined?(Sequel::Postgres) ? :timetz : :datetime

    [:foos, :bars].each do |tab|
      add_column tab, :created_at, time_type
      add_column tab, :updated_at, time_type
    end
  end

  def down
    ....
  end

end