Mysql2::Error: Index column size too large. The maximum column size is 767 bytes.: CREATE INDEX `index_xxx_yyy_id`

utf8mb4対応

MySQLのデータベース設定がutf8mb4でこのエラーが発生したら

• ROW_FORMATnのデフォルトをDYNAMIC

config/initializers/ar_innodb_row_format.rb

ActiveSupport.on_load :active_record do
  module ActiveRecord::ConnectionAdapters
    class AbstractMysqlAdapter
      def create_table_with_innodb_row_format(table_name, options = {})
        table_options = options.merge(options: 'ENGINE=InnoDB ROW_FORMAT=DYNAMIC')
        create_table_without_innodb_row_format(table_name, table_options) do |td|
          yield td if block_given?
        end
      end
      alias_method_chain :create_table, :innodb_row_format
    end
  end
end

• my.cnf
  • innodb_file_format = Barracuda
  • innodb_file_per_table = 1
  • innodb_large_prefix