    # File lib/active_record/connection_adapters/abstract/schema_definitions.rb, line 319
          def column(name, type, options = {})
            column = self[name] || ColumnDefinition.new(@base, name, type)
            column.limit = options[:limit] || native[type.to_sym][:limit] if options[:limit] or native[type.to_sym]
            column.precision = options[:precision]
            column.scale = options[:scale]
            column.default = options[:default]
            column.null = options[:null]
            @columns << column unless @columns.include? column
            self
          end