up

# File activerecord/lib/active_record/migration.rb, line 1263
    def up(target_version = nil, &block) # :nodoc:
      selected_migrations = if block_given?
        migrations.select(&block)
      else
        migrations
      end

      Migrator.new(:up, selected_migrations, schema_migration, internal_metadata, target_version).migrate
    end