temporary_table.rb

ApplicationRecord.connection.execute(
  <<~SQL
    CREATE TEMPORARY TABLE IF NOT EXISTS gadgets
    (
      id bigint NOT NULL,
      name varchar(64) NOT NULL
    );

    CREATE TEMPORARY SEQUENCE IF NOT EXISTS gadgets_id_seq
      START WITH 1
      INCREMENT BY 1
      NO MINVALUE
      NO MAXVALUE
      CACHE 1;

    ALTER SEQUENCE gadgets_id_seq OWNED BY gadgets.id;

    ALTER TABLE ONLY gadgets
      ALTER COLUMN id
      SET DEFAULT nextval('gadgets_id_seq'::regclass);
  SQL
)