run_without_lock

# File activerecord/lib/active_record/migration.rb, line 1168
    def run_without_lock
      migration = migrations.detect { |m| m.version == @target_version }
      raise UnknownMigrationVersionError.new(@target_version) if migration.nil?
      execute_migration_in_transaction(migration, @direction)

      record_environment
    end