    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 689
          def add_column(table_name, column_name, type, options = {})
            default = options[:default]
            notnull = options[:null] == false

            # Add the column.
            execute("ALTER TABLE #{quote_table_name(table_name)} ADD COLUMN #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}")

            change_column_default(table_name, column_name, default) if options_include_default?(options)
            change_column_null(table_name, column_name, false, default) if notnull
          end