Active Record postgres copy

active_record_postgres_copy_1.rb

connection = ActiveRecord::Base.connection

query = "COPY ( SELECT '#{header}' UNION ALL #{sql_query}) TO 'file.csv' WITH DELIMITER AS ',' CSV"

connection.execute query

active_record_postgres_copy_2.rb

connection = ActiveRecord::Base.connection.raw_connection

query = "COPY ( SELECT '#{header}' UNION ALL #{sql query}) TO STDOUT WITH DELIMITER AS ',' CSV"

connection.exec query

while (copy_data = connection.get_copy_data) do
# write data to file.csv
end