rails_timestamptz.rb

# with postgres DDL
execute SQL<<-
  create table users(
    ...
    created_at timestamptz not null,
    updated_at timestamptz not null
  );
SQL

# with Rails DSL
create_table :users do |t|
  ...
  t.column :created_at, 'timestamp with time zone', null: false
  t.column :updated_at, 'timestamp with time zone', null: false
end