Non-ORM import with SQL file access

import.rake

file = "/tmp/#{SecureRandom.uuid}"

select = <<~MySQL
  SELECT id + #{@user_offset}, email, name, created_at, updated_at
  FROM users
  INTO OUTFILE '#{file}_users'
  FIELDS TERMINATED BY ','
  OPTIONALLY ENCLOSED BY '"'
  LINES TERMINATED BY '\n';
MySQL

copy = <<~PostgreSQL
  COPY users (id, email, name, created_at, updated_at)
  FROM '#{file}_users'
  WITH CSV;

  SELECT setval('users_id_seq', (SELECT MAX(id) FROM users));
PostgreSQL

OLD.run(select)
ActiveRecord::Base.connection.execute(copy)